











                           TINKER






             Software Tools for Molecular Design
                         Version 3.9
                          June 2001
















         Copyright © 1990-2001 by Jay William Ponder
                     All Rights Reserved















        Copyright © 1990-2001 by Jay William Ponder
        All Rights Reserved


        User's Guide Cover Illustration by Jay Nelson
        Courtesy of Prof. R. T. Paine, Univ. of New 
        Mexico


        TINKER IS PROVIDED "AS IS" AND WITHOUT ANY 
        WARRANTY EXPRESS OR IMPLIED. THE USER ASSUMES 
        ALL RISKS OF USING THIS SOFTWARE. THERE IS NO 
        CLAIM OF THE MERCHANTABILITY OR FITNESS FOR A 
        PARTICULAR PURPOSE.

        YOU MAY MAKE COPIES OF TINKER FOR YOUR OWN 
        USE, AND MODIFY THOSE COPIES. YOU MAY NOT 
        DISTRIBUTE ANY MODIFIED SOURCE CODE OR 
        DOCUMENTATION TO USERS AT ANY SITE OTHER THAN 
        YOUR OWN.


        v3.9 6/01

                           TINKER

             Software Tools for Molecular Design
                   Version 3.9   June 2001


Table of Contents                                       Page

Introduction to the TINKER Package                        5
Installing TINKER on your Computer                        7
Types of Input & Output Files                             9
Potential Energy Programs                                12
Structure Manipulation Programs                          18
Force Field Parameter Sets                               22
Use of the Keyword Control File                          29
Notes on Special Features & Methods                      59
Descriptions of TINKER Routines                          65
Contents of Common Block Variables                      124
Index of Function & Subroutine Calls                    150
Examples using the TINKER Package                       174
Benchmark Results                                       176
Collaborators & Acknowledgments                         179
References & Suggested Reading                          181

 1.     Introduction to the TINKER Package

     Welcome  to  the  TINKER  molecular  modeling  package!  
TINKER is designed to be  an easily used and flexible system 
of  programs  and  routines   for  molecular  mechanics  and 
dynamics  as  well  as  other  energy-based  and  structural 
manipulation  calculations. It  is  intended  to be  modular 
enough to  enable development  of new  computational methods 
and  efficient enough  to meet  most production  calculation 
needs. Rather  than incorporating  all the  functionality in 
one monolithic program, TINKER  provides a set of relatively 
small   programs  that   interoperate  to   perform  complex 
computations. New  programs can be easily  added by modelers 
with  only limited  programming  experience.  The series  of 
major programs  included in the distribution  system perform 
the following core tasks:

           (1) build  protein and  nucleic acid  models from 
sequence
           (2) energy     minimization    and     structural 
optimization
           (3) analysis  of  energy  distribution  within  a 
structure
           (4) molecular dynamics and stochastic dynamics
           (5) simulated annealing with  a choice of cooling 
schedules
           (6) normal modes and vibrational frequencies
           (7) conformational search and global optimization
           (8) transition state  location and conformational 
pathways
           (9) fitting of energy parameters to crystal data
          (10) distance geometry with pairwise metrization
          (11) molecular volumes and surface areas
          (12) free energy changes for structural mutations
          (13) advanced   algorithms   based  on   potential 
smoothing

     Many of  the various energy minimization  and molecular 
dynamics computations  can be  performed on full  or partial 
structures,   over  Cartesian,   internal   or  rigid   body 
coordinates, and including a  variety of boundary conditions 
and  crystal cell  types.  Other programs  are available  to 
generate  timing  data  and   allow  checking  of  potential 
function derivatives for coding errors. Special features are 
available  to facilitate  input  and output  of protein  and 
nucleic acid  structures. However,  the basic  core routines 
have no  knowledge of biopolymer  structure and can  be used 
for general molecular systems.

     Due  to its  emphasis on  ease of  modification, TINKER 
differs  from  many   other  currently  available  molecular 
modeling packages in that the user is expected to be willing 
to  write  simple  ``front-end''   programs  and  make  some 
alterations  at the  source  code level.  The main  programs 
provided should be considered as  templates for the users to 
change  according  to  their  wishes.  All  subroutines  are 
internally documented  and structured  programming practices 
are adhered to throughout. The  result, it is hoped, will be 
a calculational system which can  be tailored to local needs 
and desires.

     The core TINKER system consists of nearly 120,000 lines 
of source written entirely in a portable Fortran77 superset. 
Use is made of only some  very common extensions that aid in 
writing highly  structured code. The current  version of the 
package has been ported to a wide range of computers with no 
or  extremely  minimal  changes.  Tested  machines  include: 
Compaq Alphas under Tru64  Unix or OpenVMS; Hewlett-Packard, 
IBM RS/6000, Silicon Graphics and Sun workstations under the 
vendor's  Unix;   Apple  Macintosh;  and  Intel   PCs  under 
Windows9X/NT/2000  and Linux.  At present,  our new  code is 
written  on Athlon  Linux  and Compaq  Alpha platforms,  and 
occasionally  tested for  compatibility  on  various of  the 
other machine and OS  combinations listed above. At present, 
we are in the process  of converting our primary development 
efforts from Fortran77  to a more modern  Fortran dialect. A 
machine-translated   C  version   of  TINKER   is  currently 
available, and  a hand-translated  optimized C version  of a 
previous  TINKER   version  is  available   for  inspection. 
Conversion to C or C++ is under consideration, but not being 
actively pursued at this time.

     The basic design of the  energy function engine used by 
the  TINKER   system  allows  usage  of   several  different 
parameter sets.  At present  we are  distributing parameters 
that implement AMBER-95, CHARMM27,  MM2, MM3, OPLS-AA, OPLS-
UA and our own TINKER  parameters. In most cases, the source 
code separates the geometric manipulations needed for energy 
derivatives  from the  actual  form of  the energy  function 
itself. Several  other literature  parameter sets  are being 
considered for future development (ENCAD, MMFF-94, MM4, UFF, 
etc.), and many of  the alternative potential function forms 
reported in  the literature  can be implemented  directly or 
after minor code changes.

     Much of  the software  in the  TINKER package  has been 
heavily used and well tested,  but some modules are still in 
a fairly  early stage  of development.  Further work  on the 
TINKER system is planned in  three main areas: (1) extension 
and improvement of the potential energy parameters including 
further  development  of  our polarizable  multipole  TINKER 
force  field, (2)  coding  of  new computational  algorithms 
including additional methods  for free energy determination, 
torsional  Monte  Carlo  and  molecular  dynamics  sampling, 
advanced  methods   for  long  range   interactions,  better 
transition state  location, and  further application  of the 
potential   smoothing  paradigm,   (3)  a   friendlier  user 
interface     for    protein/nucleic     acid/polysaccharide 
computations including  direct input/output of  Protein Data 
Bank  files,  and (4)  a  Java-based  GUI front-end  to  tie 
together  the   TINKER  programs   and  provide   for  basic 
visualization.

     Questions  and comments  regarding the  TINKER package, 
including suggestions for improvements and changes should be 
made to the author:

                  Professor Jay William Ponder
                  Biochemistry & Molecular Biophysics
                  North Building, Room 2811, Box 8231
                  Washington University School of Medicine
                  660 South Euclid Avenue
                  Saint Louis, MO  63110  U.S.A.

                  phone: (314) 362-4195
                  fax:   (314) 362-7183
                  email: ponder@dasher.wustl.edu

In  addition,  an Internet  web  site  containing an  online 
version of  this User's Guide, the  most recent distribution 
version  of  the  full   TINKER  package  and  other  useful 
information can be  found at http://dasher.wustl.edu/tinker, 
the Home Page for the TINKER Molecular Modeling Package.
 2.     Installing TINKER on your Computer

     The TINKER  package is distributed on  the Internet via 
either  the  web  site  or  the  anonymous  ftp  account  on 
dasher.wustl.edu with  an IP  number of  128.252.68.48. This 
node is an AlphaServer 4100 file server running Compaq Tru64 
Unix  located in  the  Ponder lab  at Washington  University 
School of Medicine. The package is available via the web and 
standard   browsers   from   the   TINKER   home   page   at 
http://dasher.wustl.edu/tinker. Alternatively  TINKER can be 
downloaded by logging  into dasher.wustl.edu under anonymous 
ftp  (Username: anonymous,  Password: "your  email address") 
and   downloading   the   software  from   the   /pub/tinker 
subdirectory. The  complete TINKER  distribution as  well as 
individual files can be downloaded from this site.

     On dasher.wustl.edu,  the TINKER package is  present as 
both a compressed Unix tar archive  and as a complete set of 
uncompressed source  and data  files. Binaries  are provided 
for  Intel PCs  running Windows  9X/ME/NT/2000, PCs  running 
Linux, and  for Apple  Power Macintosh running  Mac OS  9 or 
earlier. All of these  executables are available in standard 
compressed  formats as  individual programs  or as  complete 
sets of  executables. It is  expected that other  Unix users 
and PC  users who  need specially customized  versions, will 
build binaries for their  specific system. Sites with access 
to  the Unix  tar, compress  and uncompress  commands should 
simply obtain the  archive file tinker.tar.Z. Alternatively, 
a  file tinker.tar.gz  containing a  tar archive  compressed 
with GNU  gzip is also  provided. If you choose  to download 
individual files, you will need at a minimum the contents of 
the /doc, /source and  /params subdirectories. Also required 
are the  compile/build scripts  from the  subdirectory named 
for your  machine type. Other  areas contain test  cases and 
examples, benchmark results,  and machine-translated C code. 
The entire  TINKER package, after building  the executables, 
will require  from about  40 to over  100 megabytes  of disk 
space depending on  the components installed and  the use of 
shared libraries in the executables.

     The  documentation for  the TINKER  programs, including 
the  guide you  are  currently reading,  is  located in  the 
/pub/tinker/doc subdirectory. The documentation was prepared 
using the  Applixware Words and Graphics  programs. Portable 
versions of the documentation are  provided as ascii text in 
.txt files and in .ps Postscript and .pdf Adobe Acrobat file 
formats. Please read and return  by mail the TINKER license. 
While the intent is to  distribute the TINKER code to anyone 
who wants  it, the authors would  like to keep track  of the 
sites  using the  package. The  returned license  forms also 
help  us justify  further  development of  TINKER. When  new 
modules  and capabilities  become  available,  and when  the 
almost  inevitable bugs  are uncovered,  we will  attempt to 
notify those who  have returned a license  form. Finally, we 
remind you that  this software is copyrighted,  and ask that 
it not be redistributed in any form.

     The compilation and building  of the TINKER executables 
should be  easy for  most of the  common workstation  and PC 
class computers. We  provide in the /make  area a Unix-style 
Makefile that  with some modification  can be used  to build 
TINKER on  most Unix machines.  As a simpler  alternative to 
Makefiles for  the Unix  versions, we also  provide machine-
specific directories  with three  separate shell  scripts to 
compile the source, build an object library, and link binary 
executables. Three  similar command  files are  provided for 
Open VMS, and  for PC and Macintosh  systems. Compilation on 
Unix  workstations should  use the  vendor supplied  Fortran 
compiler, if  available. The  public domain GNU  g77 Fortran 
compiler available  from http://gcc.gnu.org is  also capable 
of building  TINKER on  Unix machines  and under  Linux. The 
Linux executables we  provide are built with  the either the 
Portland  Group  (PGI)  compiler or  the  Absoft  ProFortran 
compiler, both of which generate somewhat faster executables 
than  g77. For  the Macintosh  we have  favorable experience 
with  the  Absoft  ProFortran  compiler  running  under  the 
Macintosh  Programmers'  Workbench  (MPW). On  PC's  running 
Windows 9X/NT/2000,  the distributed TINKER  executables are 
built on  an Intel Pentium  III CPU under the  Compaq Visual 
Fortran 6.5 compiler. While the CVF 6.5 compiler has Athlon-
specific optimizations,  we have not yet  investigated these 
options. The Microsoft Fortran  Power Station 4.0 and Watcom 
F77 compilers  are also sufficient for  building TINKER, and 
we  provide   scripts  for  each  of   these  PC  compilers. 
Alternative   Windows   compilers   such   as   those   from 
Lahey/Fujitsu and  The Portland  Group should work  as well, 
but we  have not evaluated  them yet. Please see  the README 
files  in each  of  the machine-specific  areas for  further 
information.

     The  first step  in  building TINKER  using the  script 
files is to run the appropriate ``compile'' script. Next you 
must  use the  ``library'' script  to create  an archive  of 
object  code modules.  Finally, run  the ``link''  script to 
produce  the   complete  set  of  TINKER   executables.  The 
executables can be renamed and moved to wherever you like by 
editing and running the ``rename'' script.

     Regardless  of your  target machine,  only three  small 
pieces  of  code can  possibly  require  attention prior  to 
building. The  first two are  the system dependent  time and 
date routines found in  clock.f and calendar.f respectively. 
Please uncomment  the sections of these  routines needed for 
your computer type. The final  set of source alterations are 
the  master  array  dimensions  found in  the  include  file 
sizes.i.  The most  basic limit  is on  the number  of atoms 
allowed, ``maxatm''. This  parameter can be set  to 10000 or 
more on  most workstations. Personal computers  with minimal 
memory may need a lower limit, perhaps 1000 atoms, depending 
on  available  memory, swap  space  and  other resources.  A 
description of  the other  parameter values is  contained in 
the header of the file. Note  that in order to keep the code 
completely transparent,  TINKER does not implement  any sort 
of virtual memory or heap data structure. This requires that 
sizes.i dimensioning values be set  at least as large as the 
biggest problem you intend to run. Obviously, you should not 
set  the array  sizes to  unnecessarily large  values, since 
this  can  tax your  compute  resources  and may  result  in 
performance  degradation.  The  worst  case we  know  of  at 
present  is for  some  of the  Compaq Alpha-based  machines, 
where running  a ``small''  problem with  TINKER executables 
dimensioned to  ``large'' sizes can  result in a  25-50% CPU 
time  penalty,  especially  if  only  the  default  compiler 
options are used.

     Specific  questions about  the building  or use  of the 
TINKER      package      should     be      directed      to 
ponder@dasher.wustl.edu.   TINKER   related   questions   or 
comments  of  more  general  interest can  be  sent  to  the 
Computational Chemistry List (http://www.ccl.net) run by Jan 
Labanowski  of The  Ohio  Supercomputer  Center. The  TINKER 
developers monitor this list and will respond to the list or 
the individual poster as appropriate. 
 3.     Types of Input & Output Files

     This section describes the basic file types used by the 
TINKER package. Let's say you  wish to perform a calculation 
on a particular small organic molecule. Assume that the file 
name chosen for  our input and output files  is sample. Then 
all of  the TINKER files  will reside on the  computer under 
the  name  sample.xxx  where  .xxx is  any  of  the  several 
extension types to be described below.

SAMPLE.XYZ

The .xyz file is the basic TINKER Cartesian coordinates file 
type. It contains a title line followed by one line for each 
atom in  the structure.  Each line contains:  the sequential 
number within the  structure, an atomic symbol  or name, X-, 
Y-, and Z-coordinates,  the force field atom  type number of 
the atom, and  a list of the atoms connected  to the current 
atom.  Except  for  programs  whose basic  operation  is  in 
torsional space, all TINKER  calculations are done from some 
version of the .xyz format.

SAMPLE.INT

The   .int    file   contains   an    internal   coordinates 
representation of the molecular  structure. It consists of a 
title  line  followed by  one  line  for  each atom  in  the 
structure. Each line contains:  the sequential number within 
the structure,  an atomic  symbol or  name, the  force field 
atom type  number of the  atom, and internal  coordinates in 
the  usual  Z-matrix  format.  For each  atom  the  internal 
coordinates consist of a distance to some previously defined 
atom,  and either  two bond  angles or  a bond  angle and  a 
dihedral  angle to  previous  atoms. The  length, angle  and 
dihedral definitions  do not  have to represent  real bonded 
interactions.  Following the  last atom  definition are  two 
optional blank line separated sets of atom number pairs. The 
first  list  contains pairs  of  atoms  that are  covalently 
bonded, but  whose bond length was  not used as part  of the 
atom definitions.  These pairs  are typically used  to close 
ring structures. The second list contains ``bonds'' that are 
to be broken,  i.e., pairs of atoms that  are not covalently 
bonded, but which were used to define a distance in the atom 
definitions.

SAMPLE.KEY

The keyword parameter file always has the extension .key and 
is  optionally   present  during  TINKER   calculations.  It 
contains values  for any of  a wide variety of  switches and 
parameters  that  are  used  to change  the  course  of  the 
computation from the default.  The detailed contents of this 
file is explained in a  latter section of this User's Guide. 
If  a  molecular  system  specific  keyfile,  in  this  case 
sample.key, is not present, the the TINKER program will look 
in the same directory for a generic file named tinker.key.

SAMPLE.DYN

The .dyn file contains values  needed to restart a molecular 
or stochastic  dynamics computation.  It stores  the current 
position,   current  velocity   and  current   and  previous 
accelerations for each  atom, as well as the  size and shape 
of any periodic  box or crystal unit  cell. This information 
can be used to start a new dynamics run from the final state 
of  a  previous run.  Upon  startup,  the dynamics  programs 
always check for the presence of a .dyn file and make use of 
it whenever  possible. The  .dyn file is  updated concurrent 
with the saving of a new dynamics trajectory snapshot.

SAMPLE.END

The .end file type provides a mechanism to gracefully stop a 
running  TINKER  calculation.   At  appropriate  checkpoints 
during a calculation, TINKER will test for the presence of a 
sample.end file, and if found will terminate the calculation 
after updating the  output. The .end file can  be created at 
any time during a computation, and will be detected when the 
next checkpoint  is reached. The  file may be of  zero size, 
and its contents are unimportant.  In the current version of 
TINKER,  the   .end  mechanism  is  only   available  within 
dynamics-based programs.

SAMPLE.001, SAMPLE.002, ....

Several  types of  computations produce  files containing  a 
three or more digit extension (.001 as shown; or .002, .137, 
.5678, etc.). These are referred  to as cycle files, and are 
used to store various types  of output structures. The cycle 
files  from a  given computation  are identical  in internal 
structure to either the .xyz  or .int files described above. 
For example,  the vibrational analysis program  can save the 
tenth normal mode in  sample.010. A molecular dynamics-based 
program might  save its  tenth 0.1  picosecond frame  (or an 
energy minimizer its tenth partially minimized intermediate) 
in a file of the same name.

SAMPLE.ARC

A TINKER archive  file is simply a series  of .xyz Cartesian 
coordinate files  appended together one after  another. This 
file can be  used to condense the  results from intermediate 
stages of an optimization,  frames from a molecular dynamics 
trajectory, or set  of normal mode vibrations  into a single 
file for storage.

SAMPLE.PDB

This file  type contains  coordinate information in  the PDB 
format  developed by  the Brookhaven  Protein Data  Bank for 
deposition of model structures based on macromolecular X-ray 
diffraction and  NMR data.  Although TINKER itself  does not 
use .pdb files directly for input/output, auxiliary programs 
are provided with the  system for interconverting .pdb files 
with the .xyz format described above.

SAMPLE.SEQ

This file type contains the primary sequence of a biopolymer 
in the standard  one-letter code with 50  residues per line. 
The .seq  file for  a biopolymer is  generated automatically 
when a PDB  file is converted to TINKER .xyz  format or when 
using the PROTEIN  or NUCLEIC programs to  build a structure 
from sequence It is required for the reverse conversion of a 
TINKER file back to PDB format..

SAMPLE.FRAC

The fractional  coordinates corresponding to  the asymmetric 
unit of  a crystal unit cell  are stored in the  .frac file. 
The internal  format of this  file is identical to  the .xyz 
file; except that the  coordinates are fractional instead of 
in Angstrom units.

SAMPLE.XMOL

The ARCHIVE program has the option of converting a series of 
.xyz cycle files into an  XMakemol XYZ file. These files can 
be displayed as a movie  using the XMakemol display program. 
Note that the .xmol file format does not contain TINKER atom 
type information, so it is  not possible to convert an .xmol 
file back into a TINKER .xyz file.

SAMPLE.MSI

The ARCHIVE program has the option of converting a series of 
.xyz  cycle files  into a  MSI InsightII  coordinate archive 
file.  These files  can be  displayed as  a movie  using the 
InsightII display  program. Note  that the .msi  file format 
does not contain TINKER atom  type information, so it is not 
possible  to convert  a .msi  file back  into a  TINKER .XYZ 
file.

PARAMETER FILES

The potential  energy parameter  files distributed  with the 
TINKER package all end in  the extension .prm, although this 
is not  required by the  programs themselves. Each  of these 
files  contains   a  definition  of  the   potential  energy 
functional forms for that force  field as well as values for 
individual  energy parameters.  For example,  the mm3pro.prm 
file contains  the energy parameters and  definitions needed 
for a protein-specific version of the MM3 force field.
 4.     Potential Energy Programs

     This section of the manual contains a brief description 
of each of the TINKER  potential energy programs. A detailed 
example showing  how to  run each program  is included  in a 
later section. The programs listed below are all part of the 
main,  supported distribution.  Additional  source code  for 
various  unsupported programs  can  be found  in the  /other 
directory of the TINKER distribution.

ALCHEMY

A  simple   program  to  perform  very   basic  free  energy 
perturbation calculations.  This program is  provided mostly 
for demonstration purposes.  For  example, we use ALCHEMY in 
a molecular  modeling course laboratory exercise  to perform 
such classic mutations as chloride  to bromide and ethane to 
methanol in water. The present version uses the perturbation 
formula  and windowing  with  an explicit  mapping of  atoms 
involved  in  the  mutation  (``AMBER''-style),  instead  of 
thermodynamic integration and independent freely propagating 
groups of mutated atoms (``CHARMM''-style). Some of the code 
specific to  this program is  limited to the AMBER  and OPLS 
potential functional forms, but  could be easily generalized 
to handle other potentials. A more general and sophisticated 
version is currently under development.

ANALYZE

Provides information  about a specific  molecular structure. 
The program will ask for the name of a structure file, which 
must  be in the  TINKER .xyz  file format,  and the  type of 
analysis  desired.  Options  allow  output  of:   (1)  total 
potential energy of the system,  (2) breakdown of the energy 
by  potential function  type or  over individual  atoms, (3) 
computation of  the total dipole moment  and its components, 
moments of  inertia and radius  of gyration, (4)  listing of 
the   parameters  used   to  compute   selected  interaction 
energies, (5) energies  associated with specified individual 
interactions.

ANNEAL

Performs   a   molecular    dynamics   simulated   annealing 
computation.  The  program  starts from  a  specified  input 
molecular structure in TINKER .xyz format. The trajectory is 
updated using either a modified  Beeman or a velocity Verlet 
integration method. The annealing protocol is implemented by 
allowing smooth changes between starting and final values of 
the system temperature via  the Groningen method of coupling 
to an external bath. The  scaling can be linear or sigmoidal 
in nature.  In addition, parameters such  as cutoff distance 
can be transformed along with the temperature. The user must 
input  the desired  number of  dynamics steps  for both  the 
equilibration and  cooling phases,  a time interval  for the 
dynamics     steps,     and      an     interval     between 
coordinate/trajectory saves. All saved coordinate sets along 
the  trajectory are  placed in  sequentially numbered  cycle 
files.

DYNAMIC

Performs a  molecular dynamics  (MD) or  stochastic dynamics 
(SD)  computation.  Starts  either from  a  specified  input 
molecular  structure (an  .xyz  file) or  from a  structure-
velocity-acceleration  set saved  from  a previous  dynamics 
trajectory (a restart from a .dyn file). MD trajectories are 
propagated  using either  a  modified Beeman  or a  velocity 
Verlet  integration method.  SD is  implemented via  our own 
derivation of a velocity Verlet-based algorithm. In addition 
the program  can perform full crystal  calculations, and can 
operate in  constant energy  mode or  with maintenance  of a 
desired  temperature  and/or  pressure using  the  Groningen 
method of  coupling to external  baths. The user  must input 
the desired  number of dynamics  steps, a time  interval for 
the    dynamics    steps,    and   an    interval    between 
coordinate/trajectory  saves.  Coordinate   sets  along  the 
trajectory can be saved as sequentially numbered cycle files 
or directly to a TINKER archive  .arc file. At the same time 
that a  point along  the trajectory  is saved,  the complete 
information needed to restart the trajectory from that point 
is updated and stored in the .dyn file.

GDA

A program  to implement Straub's Gaussian  Density Annealing 
algorithm over an effective  series of analytically smoothed 
potential energy surfaces.  This method can be  viewed as an 
extended stochastic version of the diffusion equation method 
of Scheraga, et  al., and also has many  similar features to 
the TINKER  Potential Smoothing  and Search (PSS)  series of 
programs. The current version of  GDA is similar to but does 
not  exactly  reproduce  Straub's published  method  and  is 
limited to argon clusters and other simple systems involving 
only van  der Waals  interactions; further  modification and 
development of this code is currently underway in the Ponder 
research group.  As with other programs  involving potential 
smoothing,  GDA currently  requires  use  of the  smooth.prm 
force field parameters.

MINIMIZE

The  MINIMIZE  program  performs  a  limited  memory  L-BFGS 
minimization   of   an   input  structure   over   Cartesian 
coordinates  using a  modified version  of the  algorithm of 
Jorge Nocedal. The method requires only the potential energy 
and gradient at each step along the minimization pathway. It 
requires storage  space proportional to the  number of atoms 
in the structure. The  MINIMIZE procedure is recommended for 
preliminary  minimization  of  trial structures  to  an  rms 
gradient of 1.0 to 0.1 kcal/mole/Å. It has a relatively fast 
cycle time and  is tolerant of poor  initial structures, but 
converges in  a slow, linear  fashion near the  minimum. The 
user supplies the  name of the TINKER  .xyz coordinates file 
and a  target rms gradient  value at which  the minimization 
will terminate.  Output consists of  minimization statistics 
written to the  screen or redirected to an  output file, and 
the  new coordinates  written to  updated .xyz  files or  to 
cycle files.

MINIROT

The  MINIROT program  uses  the same  limited memory  L-BFGS 
method as MINIMIZE, but performs the computation in terms of 
dihedral angles instead of  Cartesian coordinates. Output is 
saved in an updated .int file or in cycle files.

MINRIGID

The MINRIGID program  is similar to MINIMIZE  except that it 
operates  on  rigid  bodies  starting  from  a  TINKER  .xyz 
coordinate file  and the rigid body  group definitions found 
in  the  corresponding .key  file.  Output  is saved  in  an 
updated .xyz file or in cycle files.

NEWTON

A  truncated  Newton   minimization  method  which  requires 
potential  energy, gradient  and  Hessian information.  This 
procedure  has significant  advantages over  standard Newton 
methods,  and  is able  to  minimize  very large  structures 
completely.  Several options  are provided  with respect  to 
minimization  method  and   preconditioning  of  the  Newton 
equations. The  default options  are recommended  unless the 
user  is  familiar  with  the math  involved.  This  program 
operates  in  Cartesian  coordinate   space  and  is  fairly 
tolerant  of   poor  input  structures.   Typical  algorithm 
iteration  times are  longer than  with nonlinear  conjugate 
gradient  or   variable  metric  methods,  but   many  fewer 
iterations are required for complete minimization. NEWTON is 
usually the  best choice  for minimizations  to the  0.01 to 
0.000001  kcal/mole/Å  level  of rms  gradient  convergence. 
Tests for  directions of negative curvature  can be removed, 
allowing   NEWTON   to   be   used   for   optimization   to 
conformational transition state  structures (this only works 
if  the  starting point  is  very  close to  the  transition 
state). Input  consists of  a TINKER .xyz  coordinates file; 
output  is  an  updated  set of  minimized  coordinates  and 
minimization statistics.

NEWTROT

The  NEWTROT program  is similar  to NEWTON  except that  it 
requires a .int file as input  and then operates in terms of 
dihedral  angles as  the minimization  variables. Since  the 
dihedral space  Hessian matrix of an  arbitrary structure is 
often indefinite, this method will often not perform as well 
as the other, simpler dihedral angle based minimizers.

OPTIMIZE

The  OPTIMIZE  program   performs  a  optimally  conditioned 
variable  metric minimization  of  an  input structure  over 
Cartesian  coordinates using  an  algorithm  due to  William 
Davidon.  The method  does  not perform  line searches,  but 
requires computation  of energies  and gradients as  well as 
storage for an  estimate of the inverse  Hessian matrix. The 
program operates on Cartesian coordinates from a TINKER .xyz 
file. OPTIMIZE  will typically converge somewhat  faster and 
more completely  than MINIMIZE.  However, the need  to store 
and manipulate  a full  inverse Hessian estimate  limits its 
use to structures  containing less than a  few hundred atoms 
on workstation class machines. As with the other minimizers, 
OPTIMIZE needs input coordinates  and an rms gradient cutoff 
criterion. The output coordinates  are saved in updated .xyz 
files or as cycle files.

OPTIROT

The OPTIROT  program is similar  to OPTIMIZE except  that it 
operates  on dihedral  angles  starting from  a TINKER  .int 
internal  coordinate  file.  This  program  is  usually  the 
preferred  method  for   most  dihedral  angle  optimization 
problems  since  Truncated  Newton methods  appear,  in  our 
hands,  to  lose  some  of their  efficacy  in  moving  from 
Cartesian to torsional coordinates.

OPTRIGID

The OPTRIGID program  is similar to OPTIMIZE  except that it 
operates  on  rigid  bodies  starting  from  a  TINKER  .xyz 
coordinate file  and the  rigid body atom  group definitions 
found in the corresponding .key  file. Output is saved in an 
updated .xyz file or in cycle files.

PATH

A program  that implements  a variant of  Elber's Lagrangian 
multiplier-based  reaction  path  following  algorithm.  The 
program takes as input a pair of structural minima as TINKER 
.xyz files,  and then generates  a user specified  number of 
points along a path  through conformational space connecting 
the input structures. The intermediate structures are output 
as TINKER  cycle files, and the  higher energy intermediates 
can  be used  as  input to  a  Newton-based optimization  to 
locate conformational transition states.

PSS

Implements our  version of a potential  smoothing and search 
algorithm   for  the   global   optimization  of   molecular 
conformation. An  initial structure in .xyz  format is first 
minimized   in  Cartesian   coordinates  on   a  series   of 
increasingly  smoothed potential  energy surfaces.  Then the 
smoothing procedure  is reversed  with minimization  on each 
successive  surface starting  from  the  coordinates of  the 
minimum on the previous surface. A local search procedure is 
used  during the  backtracking  to  explore for  alternative 
minima  better  than  the   one  found  during  the  current 
minimization. The final result is  usually a very low energy 
conformation  or,  in  favorable cases,  the  global  energy 
minimum  conformation. The  minimum  energy coordinate  sets 
found on each surface during  both the forward smoothing and 
backtracking procedures are  placed in sequentially numbered 
cycle files.

PSSRIGID

This program  implements the potential smoothing  and search 
method as described above for  the PSS program, but performs 
the computation in terms  of keyfile-defined rigid body atom 
groups instead of Cartesian  coordinates. Output is saved in 
numbered cycle files with the .xyz file format.

PSSROT

This program  implements the potential smoothing  and search 
method as described above for  the PSS program, but performs 
the computation in terms of a set of user-specified dihedral 
angles instead of Cartesian  coordinates. Output is saved in 
numbered cycle files with the .int file format.

SADDLE

A program  for the  location of a  conformational transition 
state  between two  potential energy  minima. SADDLE  uses a 
conglomeration  of ideas  from  the Bell-Crighton  quadratic 
path and  the Halgren-Lipscomb synchronous  transit methods. 
The basic idea is to  perform a nonlinear conjugate gradient 
optimization in a subspace  orthogonal to a suitably defined 
reaction  coordinate.  The  program requires  as  input  the 
coordinates (TINKER .xyz files) of the two minima and an rms 
gradient  convergence criterion  for  the optimization.  The 
current  estimate  of  the  transition  state  structure  is 
written  to  the  file TSTATE.XYZ.  Crude  transition  state 
structures  generated by  SADDLE  can  sometimes be  refined 
using  the  NEWTON  program.   Optionally,  a  scan  of  the 
interconversion pathway can be made at each major iteration.

SCAN

A  program for  general conformational  search of  an entire 
potential  energy surface  via a  basin hopping  method. The 
program takes as input a  TINKER .xyz coordinates file which 
is  then minimized  to find  the first  local minimum  for a 
search list.  A series  of activations along  various normal 
modes from this initial minimum  are used as seed points for 
additional  minimizations.  Whenever  a  previously  unknown 
local minimum  is located  it is added  to the  search list. 
When all  minima on the  search list have been  subjected to 
the normal  mode activation without locating  additional new 
minima, the program terminates.  The individual local minima 
are written to cycle files as they are discovered. While the 
SCAN program  can be  used on standard  undeformed potential 
energy  surfaces, we  have found  it to  be most  useful for 
quickly ``scanning'' a smoothed  energy surface to enumerate 
the major basins of attraction spaning the entire surface.

SNIFFER

A program  that implements  the Sniffer  global optimization 
algorithm  of Butler  and  Slaminka, a  discrete version  of 
Griewank's  global  search  trajectory method.  The  program 
takes an  input TINKER .xyz  coordinates file and  shakes it 
vigorously  via  a   modified  dynamics  trajectory  before, 
hopefully, settling into a low lying minimum. Some trial and 
error  is often  required as  the current  implementation is 
sensitive to  various parameters and tolerances  that govern 
the computation.  At present, these parameters  are not user 
accessible, and must be altered in the source code. However, 
this  method  can  do  a  good  job  of  quickly  optimizing 
conformation within a limited range of convergence.

TESTGRAD

The TESTGRAD  program computes  and compares  the analytical 
and numerical first derivatives  (i.e., the gradient vector) 
of  the potential  energy for  a Cartesian  coordinate input 
structure.  The output  can be  used  to test  or debug  the 
current potential or any added user defined energy terms.

TESTHESS

The TESTHESS  program computes  and compares  the analytical 
and numerical second derivatives  (i.e., the Hessian matrix) 
of  the potential  energy for  a Cartesian  coordinate input 
structure.  The output  can be  used  to test  or debug  the 
current potential or any added user defined energy terms.

TESTLIGHT

A program  to compare the efficiency  of different nonbonded 
neighbor  methods  for  the current  molecular  system.  The 
program times the computation of energy and gradient for the 
van  der  Waals  and charge-charge  electrostatic  potential 
terms using a  simple double loop over  all interactions and 
using the  Method of  Lights algorithm to  select neighbors. 
The  results can  be used  to decide  whether the  Method of 
Lights has any CPU time advantage for the current structure. 
Both  methods should  give exactly  the same  answer in  all 
cases,  since  the  identical  individual  interactions  are 
computed by both methods. The  default double loop method is 
faster when cutoffs are not  used, or when the cutoff sphere 
contains  about half  or more  of the  total system  of unit 
cell. In cases where the  cutoff sphere is much smaller than 
the system  size, the  Method of Lights  can be  much faster 
since it avoids unnecessary  calculation of distances beyond 
the cutoff range.

TESTROT

The TESTROT program computes and compares the analytical and 
numerical first  derivatives (i.e., the gradient  vector) of 
the potential energy with  respect to dihedral angles. Input 
is a TINKER .int internal coordinate file. The output can be 
used to test or debug the current potential functions or any 
added user defined energy terms.

TIMER

A  simple program  to provide  timing statistics  for energy 
function calls within the  TINKER package. TIMER requires an 
input .xyz file and outputs the CPU time (wall clock time on 
some machine types) needed to  perform a specified number of 
energy, gradient and Hessian evaluations.

TIMEROT

This  program is  similar to  TIMER, only  it operates  over 
dihedral  angles  via  input   of  a  TINKER  .int  internal 
coordinate  file.  In  the current  version,  the  torsional 
Hessian   is  computed   numerically  from   the  analytical 
torsional gradient.

VIBRATE

A program  to perform vibrational analysis  by computing and 
diagonalizing  the full  Hessian  matrix  (i.e., the  second 
partial derivatives)  for an input structure  (a TINKER .xyz 
file).  Eigenvalues and  eigenvectors of  the mass  weighted 
Hessian (i.e., the vibrational frequencies and normal modes) 
are also calculated.  Structures corresponding to individual 
normal mode motions can be saved in cycle files.

VIBROT

The program  VIBROT forms  the torsional Hessian  matrix via 
numerical  differentiation   of  the   analytical  torsional 
gradient.  The   Hessian  is   then  diagonalized   and  the 
eigenvalues are output. The present version does not compute 
the  kinetic energy  matrix elements  needed to  convert the 
Hessian into the torsional normal  modes; this will be added 
in  a later  version. The  required input  is a  TINKER .int 
internal coordinate file.

XTALFIT

The XTALFIT  program is of  use in the automated  fitting of 
potential parameters to  crystal structure and thermodynamic 
data.  XTALFIT takes  as  input  several crystal  structures 
(TINKER   .xyz   files   with  unit   cell   parameters   in 
corresponding keyfiles)  as well  as information  on lattice 
energies and dipole moments of monomers. The current version 
uses a nonlinear  least squares optimization to  fit van der 
Waals and electrostatic parameters to the input data. Bounds 
can be placed on the values of the optimization parameters.

XTALMIN

A program to perform full crystal minimizations. The program 
takes  as  input the  structure  coordinates  and unit  cell 
lattice  parameters. It  then alternates  cycles of  Newton-
style optimization  of the structure and  conjugate gradient 
optimization  of   the  crystal  lattice   parameters.  This 
alternating   minimization  is   slower  than   more  direct 
optimization of all parameters at once, but is somewhat more 
robust in our hands. The symmetry of the original crystal is 
not  enforced, so  interconversion of  crystal forms  may be 
observed in some cases.
 5.     Structure Manipulation Programs

     This section of the manual contains a brief description 
of  each of  the  TINKER  structure manipulation,  geometric 
calculation  and  auxiliary  programs.  A  detailed  example 
showing  how to  run each  program  is included  in a  later 
section. The programs listed below are all part of the main, 
supported distribution.  Additional source code  for various 
unsupported programs can be found in the /other directory of 
the TINKER distribution.

ARCHIVE

A program for concatenating TINKER cycle files into a single 
archive file; useful for storing the intermediate results of 
minimizations, dynamics trajectories, and so on. The archive 
file can be  written in TINKER format, or  in formats usable 
with MSI's InsightII (their CAR file with .msi extension) or 
with XMakemol (their file format with .xmol extension). Only 
active  atoms are  written into  the InsightII  and XMakemol 
output files,  allowing display  of partial  structures. The 
program  can  also extract  individual  cycle  files from  a 
TINKER archive.

CORRELATE

A  program  to  compute   time  correlation  functions  from 
collections of TINKER  cycle files. Its use  requires a user 
supplied function  property that  computes the value  of the 
property for  which a  time correlation  is desired  for two 
input structures. A sample routine is supplied that computes 
either  a  velocity  autocorrelation   function  or  an  rms 
structural  superposition as  a function  of time.  The main 
body of the program organizes  the overall computation in an 
efficient  manner and  outputs  the  final time  correlation 
function.

CRYSTAL

A  program  for  the   manipulation  of  crystal  structures 
including  interconversion   of  fractional   and  Cartesian 
coordinates, generation of the  unit cell from an asymmetric 
unit, and building of a  crystalline block of specified size 
via replication of  a single unit cell.  The present version 
can handle about 25 of  the most common space groups, others 
can easily be added as needed by modification of the routine 
symmetry.

DIFFUSE

A  program  to compute  the  self-diffusion  constant for  a 
homogeneous liquid  via the Einstein equation.  A previously 
saved  dynamics trajectory  is read  in and  ``unfolded'' to 
reverse  translation of  molecules  due to  use of  periodic 
boundary conditions.  The average motion over  all molecules 
is then  used to compute the  self-diffusion constant. While 
the current program assumes  a homogeneous system, it should 
be easy to modify the code to handle diffusion of individual 
molecules or other desired effects.

DISTGEOM

A program  to perform  distance geometry  calculations using 
variations  on  the classic  metric  matrix  method. A  user 
specified number of structures consistent with keyfile input 
distance and  dihedral restraints is generated.  Bond length 
and angle  restraints are derived from  the input structure. 
Trial  distances between  the  triangle  smoothed lower  and 
upper bounds  can be chosen  via any of  several metrization 
methods, including a very  effective partial random pairwise 
scheme. The correct  radius of gyration of  the structure is 
automatically  maintained by  choosing trial  distances from 
Gaussian distributions  of appropriate  mean and  width. The 
initial embedded structures can be further refined against a 
geometric restraint-only potential using either a sequential 
minimization protocol or simulated annealing.

DOCUMENT

The DOCUMENT  program is provided  as a minimal  listing and 
documentation tool.  It operates on the  TINKER source code, 
either  individual  files  or the  complete  source  listing 
produced  by the  command script  listing.make, to  generate 
lists  of  routines, common  blocks  or  valid keywords.  In 
addition, the program has the  ability to output a formatted 
parameter listing from the standard TINKER parameter files.

INTEDIT

A program to allow  interactive inspection and alteration of 
the internal  coordinate definitions and values  of a TINKER 
structure. If  the structure  is altered,  the user  has the 
option to  write out  a new  internal coordinates  file upon 
exit.

INTXYZ

A  program to  convert  a TINKER  .int internal  coordinates 
formatted  file into  a  TINKER  .xyz Cartesian  coordinates 
formatted file.

NUCLEIC

A program for automated building of nucleic acid structures. 
Upon  interactive  input  of   a  nucleotide  sequence  with 
optional  phosphate  backbone  angles,  the  program  builds 
internal  and Cartesian  coordinates. Standard  bond lengths 
and  angles  are  used.  Both  DNA  and  RNA  sequences  are 
supported  as  are  A-,  B- and  Z-form  structures.  Double 
helixes  of  complementary  sequence  can  be  automatically 
constructed via a rigid docking of individual strands.

PDBXYZ

A program for converting a Brookhaven Protein Data Bank file 
(a PDB file)  into a TINKER .xyz  Cartesian coordinate file. 
If  the PDB  file contains  only protein/peptide  amino acid 
residues, then standard protein connectivity is assumed, and 
transferred to  the .xyz  file. For non-protein  portions of 
the PDB file, atom connectivity is determined by the program 
based  on interatomic  distances. The  program also  has the 
ability to  add or remove  hydrogen atoms from a  protein as 
required   by  the   force   field   specified  during   the 
computation.

POLARIZE

A  program for  computing molecular  polarizability from  an 
atom-based  distributed model  of  polarizability. A  damped 
interaction  model due  to Thole  is optionally  via keyfile 
settings.  A TINKER  .xyz  file is  required  as input.  The 
output consists of the  overall polarizability tensor in the 
global coordinates and its eigenvalues.

PROTEIN

A  program for  automated  building of  peptide and  protein 
structures. Upon interactive input of an amino acid sequence 
with optional phi/psi/omega/chi angles, D/L chirality, etc., 
the  program  builds  internal  and  Cartesian  coordinates. 
Standard  bond  lengths  and  angles  are  assumed  for  the 
peptide. The  program will optionally convert  the structure 
to a cyclic peptide, or add either or both N- and C-terminal 
capping groups. Atom type numbers are automatically assigned 
for the specified  force field. The final  coordinates and a 
sequence file are produced as the output.

RADIAL

A program  to compute the pair  radial distribution function 
between two atom types. The user supplies the two atom names 
for which the  distribution function is to  be computed, and 
the  width  of  the  distance  bins  for  data  analysis.  A 
previously saved  dynamics trajectory is read  as input. The 
raw radial  distribution and  a spline smoothed  version are 
then  output from  zero  to  a distance  equal  to half  the 
minimum periodic  box dimension. The atom  names are matched 
to the atom name column of the TINKER .xyz file, independent 
of atom type.

SPACEFILL

A  program  to  compute  the volume  and  surface  areas  of 
molecules. Using  a modified version of  Connolly's original 
analytical description of the molecular surface, the program 
determines either the van der Waals, accessible or molecular 
(contact/reentrant)  volume and  surface area.  Both surface 
area  and  volume  are  broken  down  into  their  geometric 
components, and  surface area is decomposed  into the convex 
contribution for  each individual atom. The  probe radius is 
input as a user option, and  atomic radii can be set via the 
keyword file. If TINKER archive files are used as input, the 
program will  compute the  volume and  surface area  of each 
structure in the input file.

SPECTRUM

A  program  to  compute   a  power  spectrum  from  velocity 
autocorrelation  data. As  input,  this  program requires  a 
velocity  autocorrelation   function  as  produced   by  the 
CORRELATE program. This  data, along with a  user input time 
step,  are  Fourier  transformed to  generate  the  spectral 
intensities over a  wavelength range. The result  is a power 
spectrum, and the positions of the bands are those predicted 
for an infrared or Raman  spectrum. However, the data is not 
weighted by molecular dipole  moment derivatives as would be 
required to produce correct IR intensities.

SUPERPOSE

A  program to  superimpose  two molecular  structures in  3-
dimensions. A variety of options  for input of the atom sets 
to   be  used   during  the   superposition  are   presented 
interactively to  the user.  The superposition can  be mass-
weighted  if  desired, and  the  coordinates  of the  second 
structure superimposed on the first structure are optionally 
output.  If TINKER  archive  files are  used  as input,  the 
program  will compute  all  pairwise superpositions  between 
structures in the input files.

SYBYLXYZ

A program  for converting  a TRIPOS Sybyl  MOL2 file  into a 
TINKER .xyz  Cartesian coordinate file. The  current version 
of the program  does not attempt to convert  the Sybyl atoms 
types into  the active TINKER  force field types,  i.e., all 
atoms types are simply set to zero.

TVIEW

This is  a molecule viewing  program derived from  the well-
know Rasmol  program of  Roger Sayle.  TVIEW is  modified to 
remove most of the  protein-specific options and to directly 
read  the  TINKER  .xyz  file format.  The  original  RasMol 
program   has   been   altered  to   allow   selection   and 
specification  by  atoms instead  of  residues.  We hope  to 
provide  additional  functionality  in  future  versions  of 
TVIEW,  especially the  ability  to animate  the viewing  of 
sequences  of coordinate  snapshots from  a minimization  or 
dynamic trajectory.

XYZEDIT

A program that performs and of a variety of manipulations on 
an input  TINKER .xyz Cartesian coordinates  formatted file. 
The  present  version  of  the  program  has  the  following 
interactively selectable options: (1)  Offset the Numbers of 
the  Current Atoms,  (2)  Deletion  of Individual  Specified 
Atoms,  (3)  Deletion  of  Specified  Types  of  Atoms,  (4) 
Deletion  of Atoms  outside Cutoff  Range, (5)  Insertion of 
Individual Specified Atoms, (6) Replace Old Atom Type with a 
New Type,  (7) Assign Connectivities based  on Distance, (8) 
Convert  Units  from Bohrs  to  Angstroms,  (9) Invert  thru 
Origin to give  Mirror Image, (10) Translate  Center of Mass 
to  the  Origin, (11)  Translate  a  Specified Atom  to  the 
Origin, (12)  Translate and  Rotate to Inertial  Frame, (13) 
Move to  Specified Rigid  Body Coordinates, (14)  Create and 
Fill a Periodic Boundary Box,  (15) Soak Current Molecule in 
Box of Solvent, (16) Append another XYZ file to Current One. 
In most cases, multiply  options can be applied sequentially 
to an input  file. At the end of the  editing process, a new 
version of the original .xyz file is written as output.

XYZINT

A program for converting  a TINKER .xyz Cartesian coordinate 
formatted  file  into  a TINKER  .int  internal  coordinates 
formatted file.

XYZPDB

A program for converting  a TINKER .xyz Cartesian coordinate 
file into a Brookhaven Protein Data Bank file (a PDB file).

XYZSYBYL

A  program to  convert a  TINKER .xyz  Cartesian coordinates 
file into a TRIPOS Sybyl MOL2 file. The conversion generates 
only the  MOLECULE, ATOM, BOND and  SUBSTRUCTURE record type 
in the MOL2 file. Generic Sybyl  atom types are used in most 
cases; while these atom types may need to be altered in some 
cases,  Sybyl  is  usually  able to  correctly  display  the 
resulting MOL2 file.
 6.     Force Field Parameter Sets

     The TINKER  package is  distributed with  several force 
field  parameter sets,  implementing a  selection of  widely 
used literature  force fields  as well  as the  TINKER force 
field currently under construction in the Ponder lab. We try 
to exactly reproduce  the intent of the  original authors of 
our distributed, third-party force  fields. In all cases the 
parameter  sets  have   been  validated  against  literature 
reports,  results provided  by the  original developers,  or 
calculations made with the  authentic programs. With the few 
exceptions noted  below, TINKER calculations can  be treated 
as authentic results from the  genuine force fields. A brief 
description of  each parameter set, including  some still in 
preparation and not distributed with the current version, is 
provided below with lead literature references for the force 
field:

AMBER.PRM

AMBER-94/96 parameters for proteins  and nucleic acids. Note 
that with  their ``Cornell'' force field,  the Kollman group 
has  devised  separate,  fully  independent  partial  charge 
values  for  each  of  the  N-  and  C-terminal  amino  acid 
residues.  At  present,  the terminal  residue  charges  for 
TINKER's  version maintain  the correct  formal charge,  but 
redistributed somewhat  at the  alpha carbon atoms  from the 
Kollman   group  values.   The   total   magnitude  of   the 
redistribution is  less than  0.01 electrons in  most cases. 
The file provided with TINKER reproduces the original parm94 
set;  torsional parameter  changes for  parm96 are  noted in 
that  section of  the  file. The  newer, polarizable  parm99 
parameter set is not distributed  with TINKER at the present 
time.

W. D. Cornell,  P. Cieplak, C. I. Bayly, I.  R. Gould, K. M. 
Merz, Jr., D.  M. Ferguson, D. C. Spellmeyer, T.  Fox, J. W. 
Caldwell and P. A. Kollman,  A Second Generation Force Field 
for the  Simulation of Proteins, Nucleic  Acids, and Organic 
Molecules,  J.   Am.  Chem.  Soc.,  117,   5179-5197  (1995)  
[PARM94]

P. Kollman, R.  Dixon, W. Cornell, T. Fox, C.  Chipot and A. 
Pohorille,  The Development/  Application of  a 'Minimalist' 
Organic/Biochemical Molecular  Mechanic Force Field  using a 
Combination of ab Initio Calculations and Experimental Data, 
in Computer  Simulation of  Biomolecular Systems, W.  F. van 
Gunsteren, P.  K. Weiner, A.  J. Wilkinson, eds.,  Volume 3, 
83-96 (1997)  [PARM96]

G. Moyna,  H. J. Williams,  R. J.  Nachman and A.  I. Scott, 
Conformation  in Solution  and  Dynamics  of a  Structurally 
Constrained  Linear  Insect   Kinin  Pentapeptide  Analogue, 
Biopolymers, 49, 403-413 (1999)  [AIB charges]

W. S.  Ross and C.  C. Hardin, Ion-Induced  Stabilization of 
the G-DNA  Quadruplex: Free Energy Perturbation  Studies, J. 
Am. Chem. Soc., 116, 4363-4366 (1994)   [alkali metal ions]

J.  Aqvist, Ion-Water  Interaction  Potentials Derived  from 
Free Energy  Perturbation Simulations,  J. Phys.  Chem., 94, 
8021-8024,  1990  [alkaline  earth Ions,  radii adapted  for 
AMBER combining rule]

Current   force  field   parameter   values  and   suggested 
procedures  for  development  of parameters  for  additional 
molecules are  available from  the AMBER  web site  at UCSF, 
http://www.amber.ucsf.edu/amber/amber.html/

CHARMM.PRM

CHARMM27 parameters for proteins.  Most of the nucleic acid, 
lipid  and  small  model  compound parameters  are  not  yet 
implemented. We  plan to  provide the CHARMM27  nucleic acid 
parameters in due course as a separate parameter file.

N.  Foloppe and  A.  D. MacKerell,  Jr., All-Atom  Empirical 
Force  Field for  Nucleic Acids:  1) Parameter  Optimization 
Based on  Small Molecule and Condensed  Phase Macromolecular 
Target Data, J. Comput. Chem., 21, 86-104 (2000)  [CHARMM27]

N.  Banavali and  A. D.  MacKerell, Jr.,  All-Atom Empirical 
Force Field  for Nucleic Acids: 2)  Application to Molecular 
Dynamics Simulations of DNA and  RNA in Solution, J. Comput. 
Chem., 21, 105-120 (2000)

A. D. MacKerrell, Jr.,  et al., All-Atom Empirical Potential 
for Molecular Modeling and  Dynamics Studies of Proteins, J. 
Phys. Chem. B, 102, 3586-3616 (1998)  [CHARMM22]

A. D. MacKerell, Jr., J. Wiorkeiwicz-Kuczera and M. Karplus, 
An All-Atom Empirical Energy  Function for the Simulation of 
Nucleic Acids, J. Am. Chem. Soc., 117, 11946-11975 (1995)

S. E. Feller, D. Yin, R. W. Pastor and A. D. MacKerell, Jr., 
Molecular Dynamics  Simulation of Unsaturated Lipids  at Low 
Hydration: Parametrization  and Comparison  with Diffraction 
Studies,   Biophysical   Journal,   73,   2269-2279   (1997)  
[alkenes]

R. H.  Stote and  M. Karplus, Zinc  Binding in  Proteins and 
Solution -  A Simple but Accurate  Nonbonded Representation, 
Proteins, 23, 12-31 (1995)  [zinc ion]

Current and  legacy parameter values are  available from the 
CHARMM force  field web  site on Alex  MacKerell's  Research 
Interests  page  at the  University  of  Maryland School  of 
Pharmacy, 
https://rxsecure.umaryland.edu/research/amackere/research.h-
tml/

DUDEK.PRM

Protein-only parameters  for the  early 1990's  TINKER force 
field with multipole values of Dudek and Ponder. The current 
file contains only the multipole  values from the 1995 paper 
by Dudek and Ponder. This set is now superceeded by the more 
recent  TINKER  force field  developed  by  Pengyu Ren  (see 
WATER.PRM, below).

M.  J.  Dudek  and  J.  W.  Ponder,  Accurate  Electrostatic 
Modelling  of  the  Intramolecular Energy  of  Proteins,  J. 
Comput. Chem., 16, 791-816 (1995)

EMR.PRM

Reduced EMR  model adapted  for flexible sidechains.  Only a 
few amino acid residue types have been implemented.

R. V. Pappu, W. J. Schneller and D. L. Weaver, Electrostatic 
Multipole   Representation  of   a  Polypeptide   Chain:  An 
Algorithm  for  Simulation  of  Polypeptide  Properties,  J. 
Comput. Chem., 17, 1033-1055 (1996)

ENCAD.PRM

ENCAD  parameters  for  proteins  and  nucleic  acids.   (in 
preparation)

M. Levitt, M. Hirshberg, R. Sharon and V. Daggett, Potential 
Energy  Function  and  Parameters  for  Simulations  of  the 
Molecular Dynamics of Protein and Nucleic Acids in Solution, 
Comp. Phys. Commun., 91, 215-231 (1995)

M.  Levitt, M.  Hirshberg, R.  Sharon, K.  E. Laidig  and V. 
Daggett,  Calibration  and  Testing  of a  Water  Model  for 
Simulation of the Molecular  Dynamics of Protein and Nucleic 
Acids in Solution,  J. Phys. Chem. B,  101, 5051-5061 (1997)  
[F3C water]

HOCH.PRM

Simple NMR-NOE force field of Hoch and Stern.

J. C. Hoch and A. S. Stern, A Method for Determining Overall 
Protein Fold  from NMR Distance Restraints,  J. Biomol. NMR, 
2, 535-543 (1992)

MERCK.PRM

Preliminary   MMFF  vdw   parameters  using   buffered  14/7 
function.

T.  A.  Halgren,  Representation  of  van  der  Waals  (vdW) 
Interactions in Molecular  Mechanics Force Fields: Potential 
Form, Combination  Rules, and  vdW Parameters, J.  Am. Chem. 
Soc., 114, 7827-7843 (1992)

MM2.PRM

Full MM2(1991) parameters  including p-systems. The anomeric 
and  electronegativity  correction  terms included  in  some 
later versions of MM2 are not implemented.

N.  L.  Allinger,  Conformational   Analysis.  130.  MM2.  A 
Hydrocarbon Force Field Utilizing V1 and V2 Torsional Terms, 
J. Am. Chem. Soc., 99, 8127-8134 (1977)

J. T.  Sprague, J. C.  Tai, Y. Yuh  and N. L.  Allinger, The 
MMP2  Calculational Method,  J.  Comput.  Chem., 8,  581-603 
(1987)

J.  C.   Tai  and   N.  L.  Allinger,   Molecular  Mechanics 
Calculations on Conjugated Nitrogen-Containing Heterocycles, 
J. Am. Chem. Soc., 110, 2050-2055 (1988)

J.  C.  Tai, J.-H.  Lii  and  N.  L. Allinger,  A  Molecular 
Mechanics  (MM2)  Study  of Furan,  Thiophene,  and  Related 
Compounds, J. Comput. Chem., 10, 635-647 (1989)

N. L. Allinger,  R. A. Kok and M. R.  Imam, Hydrogen Bonding 
in MM2, J. Comput. Chem., 9, 591-595 (1988)

L.  Norskov-Lauritsen  and  N.   L.  Allinger,  A  Molecular 
Mechanics  Treatment  of  the Anomeric  Effect,  J.  Comput. 
Chem., 5, 326-335 (1984)

All parameters  distributed with  TINKER are from  the ``MM2 
(1991)  Parameter  Set'', as  provided  by  N. L.  Allinger, 
University of Georgia

MM3.PRM

Full   MM3(2000)   parameters  including   pi-systems.   The 
directional hydrogen bonding term and electronegativity bond 
length  corrections are  implemented, but  the anomeric  and 
Bohlmann correction terms are not implemented.

N.  L.  Allinger,  Y.  H.   Yuh  and  J.-H.  Lii,  Molecular 
Mechanics. The MM3  Force Field for Hydrocarbons.  1, J. Am. 
Chem. Soc., 111, 8551-8566 (1989)

J.-H. Lii and  N. L. Allinger, Molecular  Mechanics. The MM3 
Force Field for Hydrocarbons. 2. Vibrational Frequencies and 
Thermodynamics, J. Am. Chem. Soc., 111, 8566-8575 (1989)

J.-H. Lii and  N. L. Allinger, Molecular  Mechanics. The MM3 
Force  Field  for  Hydrocarbons.   3.  The  van  der  Waals' 
Potentials  and  Crystal  Data for  Aliphatic  and  Aromatic 
Hydrocarbons, J. Am. Chem. Soc., 111, 8576-8582 (1989)

N. L. Allinger, H. J. Geise, W. Pyckhout, L. A. Paquette and 
J. C.  Gallucci, Structures of Norbornane  and Dodecahedrane 
by   Molecular    Mechanics   Calculations    (MM3),   X-ray 
Crystallography,  and  Electron  Diffraction, J.  Am.  Chem. 
Soc., 111, 1106-1114 (1989)  [stretch-torsion cross term]

N. L. Allinger,  F. Li and L. Yan,  Molecular Mechanics. The 
MM3 Force Field  for Alkenes, J. Comput.  Chem., 11, 848-867 
(1990)

N.  L. Allinger,  F. Li,  L. Yan  and J.  C. Tai,  Molecular 
Mechanics (MM3) Calculations  on Conjugated Hydrocarbons, J. 
Comput. Chem., 11, 868-895 (1990)

J.-H. Lii  and N. L. Allinger,  Directional Hydrogen Bonding 
in the MM3  Force Field. I, J. Phys. Org.  Chem., 7, 591-609 
(1994)

J.-H. Lii  and N. L. Allinger,  Directional Hydrogen Bonding 
in the MM3 Force Field.  II, J. Comput. Chem., 19, 1001-1016 
(1998)

All parameters  distributed with  TINKER are from  the ``MM3 
(2000)  Parameter  Set'', as  provided  by  N. L.  Allinger, 
University of Georgia, August 2000

MM3PRO.PRM

Protein-only version of the MM3 parameters.

J.-H.  Lii and  N.  L.  Allinger, The  MM3  Force Field  for 
Amides,  Polypeptides and  Proteins, J.  Comput. Chem.,  12, 
186-199 (1991)

MMFFPRO.PRM

Protein-only   version  of   the  MMFF94   parameters.   (in 
preparation)

T. A. Halgren, Merck Molecular  Force Field. I. Basis, Form, 
Scope,  Parameterization,  and  Performance  of  MMFF94,  J. 
Comput. Chem., 17, 490-519, 1996

OPLS.PRM

Complete  OPLS-UA with  united-atom parameters  for proteins 
and many classes of organic molecules. Explicit hydrogens on 
polar atoms and aromatic carbons.

W.  L. Jorgensen  and  J. Tirado-Rives,  The OPLS  Potential 
Functions for Proteins. Energy Minimizations for Crystals of 
Cyclic Peptides and  Crambin, J. Am. Chem.  Soc., 110, 1657-
1666 (1988)  [peptide and proteins]

W.  L.  Jorgensen  and D.  L.  Severance,  Aromatic-Aromatic 
Interactions: Free Energy Profiles  for the Benzene Dimer in 
Water, Chloroform,  and Liquid  Benzene, J. Am.  Chem. Soc., 
112, 4768-4774 (1990)  [aromatic hydrogens]

S. J.  Weiner, P. A.  Kollman, D. A.  Case, U. C.  Singh, C. 
Ghio, G. Alagona, S. Profeta, Jr. and P. Weiner, A New Force 
Field for  Molecular Mechanical Simulation of  Nucleic Acids 
and  Proteins,  J.  Am.  Chem.  Soc.,  106,  765-784  (1984)  
[united-atom ``AMBER/OPLS'' local geometry]

S. J. Weiner, P. A. Kollman, D. T. Nguyen and D. A. Case, An 
All Atom Force Field for Simulations of Proteins and Nucleic 
Acids,  J.  Comput.  Chem.,  7,  230-252  (1986)   [all-atom 
"AMBER/OPLS" local geometry]

L. X.  Dang and B.  M. Pettitt, Simple  Intramolecular Model 
Potentials for  Water, J. Phys. Chem.,  91, 3349-3354 (1987)  
[flexible TIP3P and SPC water]

W. L. Jorgensen,  J. D. Madura and C.  J. Swenson, Optimized 
Intermolecular Potential Functions  for Liquid Hydrocarbons, 
J. Am. Chem. Soc., 106, 6638-6646 (1984)  [hydrocarbons]

W. L.  Jorgensen, E. R. Laird,  T. B. Nguyen and  J. Tirado-
Rives, Monte  Carlo Simulations  of Pure  Liquid Substituted 
Benzenes with  OPLS Potential  Functions, J.  Comput. Chem., 
14, 206-215 (1993)  [substituted benzenes]

E.  M.  Duffy, P.  J.  Kowalczyk  and  W. L.  Jorgensen,  Do 
Denaturants Interact  with Aromatic Hydrocarbons  in Water?, 
J.  Am.   Chem.  Soc.,  115,  9271-9275   (1993)   [benzene, 
naphthalene, urea, guanidinium, tetramethyl ammonium]

W. L. Jorgensen and  C. J. Swenson, Optimized Intermolecular 
Potential Functions  for Amides and Peptides.  Structure and 
Properties of Liquid Amides, J. Am. Chem. Soc., 106, 765-784 
(1984)  [amides]

W. L. Jorgensen, J. M.  Briggs and M. L. Contreras, Relative 
Partition  Coefficients  for   Organic  Solutes  form  Fluid 
Simulations,   J.   Phys.   Chem.,  94,   1683-1686   (1990)  
[chloroform, pyridine, pyrazine, pyrimidine]

J. M. Briggs, T. B. Nguyen  and W. L. Jorgensen, Monte Carlo 
Simulations of  Liquid Acetic  Acid and Methyl  Acetate with 
the OPLS Potential Functions,  J. Phys. Chem., 95, 3315-3322 
(1991)  [acetic acid, methyl acetate]

H. Liu,  F. Muller-Plathe and  W. F. van Gunsteren,  A Force 
Field for Liquid Dimethyl  Sulfoxide and Physical Properties 
of  Liquid  Dimethyl  Sulfoxide Calculated  Using  Molecular 
Dynamics  Simulation,  J.  Am. Chem.  Soc.,  117,  4363-4366 
(1995)  [dimethyl sulfoxide]

J. Gao, X.  Xia and T. F. George,  Importance of Bimolecular 
Interactions in Developing Empirical Potential Functions for 
Liquid  Ammonia,  J.  Phys.   Chem.,  97,  9241-9246  (1993)  
[ammonia]

J.  Aqvist, Ion-Water  Interaction  Potentials Derived  from 
Free Energy  Perturbation Simulations,  J. Phys.  Chem., 94, 
8021-8024 (1990)  [metal ions]

W. S.  Ross and C.  C. Hardin, Ion-Induced  Stabilization of 
the G-DNA  Quadruplex: Free Energy Perturbation  Studies, J. 
Am. Chem. Soc., 116, 4363-4366 (1994)  [alkali metal ions]

J.  Chandrasekhar, D.  C.  Spellmeyer and  W. L.  Jorgensen, 
Energy Component  Analysis for  Dilute Aqueous  Solutions of 
Li+, Na+, F-, and Cl- Ions,  J. Am. Chem. Soc., 106, 903-910 
(1984)  [halide ions]

Most parameters distributed with  TINKER are from ``OPLS and 
OPLS-AA Parameters for Organic  Molecules, Ions, and Nucleic 
Acids''  as provided  by W.  L. Jorgensen,  Yale University, 
October 1997

OPLSAA.PRM

OPLS-AA  with  all-atom  parameters for  proteins  and  many 
general classes of organic molecules.

W.  L.  Jorgensen,  D.   S.  Maxwell  and  J.  Tirado-Rives, 
Development and Testing of the  OPLS All-Atom Force Field on 
Conformational Energetics and Properties of Organic Liquids, 
J. Am. Chem. Soc., 117, 11225-11236 (1996)

W. L. Jorgensen  and N. A. McDonald, Development  of an All-
Atom  Force Field  for  Heterocycles.  Properties of  Liquid 
Pyridine and  Diazenes, THEOCHEM-J. Mol. Struct.,  424, 145-
155 (1998)

N. A. McDonald  and W. L. Jorgensen, Development  of an All-
Atom  Force Field  for  Heterocycles.  Properties of  Liquid 
Pyrrole, Furan,  Diazoles, and  Oxazoles, J. Phys.  Chem. B, 
102, 8049-8059 (1998)

All parameters  distributed with TINKER are  from ``OPLS and 
OPLS-AA Parameters for Organic  Molecules, Ions, and Nucleic 
Acids''  as provided  by W.  L. Jorgensen,  Yale University, 
October 1997

SMOOTH.PRM

Version of OPLS-UA for use with potential smoothing. Largely 
adapted  largely  from   standard  OPLS-UA  parameters  with 
modifications to the vdw and improper torsion terms.

R.  V. Pappu,  R. K.  Hart and  J. W.  Ponder, Analysis  and 
Application of Potential Energy Smoothing and Search Methods 
for Global  Optimization, J.  Phys, Chem. B,  102, 9725-9742 
(1998)  [smoothing modifications]

SMOOTHAA.PRM

Version of OPLS-AA for use with potential smoothing. Largely 
adapted  largely  from   standard  OPLS-AA  parameters  with 
modifications to the vdw and improper torsion terms.

R.  V. Pappu,  R. K.  Hart and  J. W.  Ponder, Analysis  and 
Application of Potential Energy Smoothing and Search Methods 
for Global  Optimization, J.  Phys, Chem. B,  102, 9725-9742 
(1998)  [smoothing modifications]

TINKER.PRM

Preliminary parameters for  the TINKER polarizable multipole 
force field. As the release  of TINKER 3.9 we have completed 
parametrization for  over 50  small molecule  systems, aimed 
toward  the  first  version  of a  TINKER  force  field  for 
proteins and  peptides. For  further information, or  if you 
are  interested  in testing  a  beta  parameter set,  please 
contact the TINKER developers.

WATER.PRM

The  current  TINKER  water  parameters  for  a  polarizable 
multipole  electrostatics  model.  This model  is  equal  or 
better to the best available  water models for many bulk and 
cluster properties.

Y. Kong and J. W.  Ponder, Calculation of the Reaction Field 
Due  to Off-Center  Point Multipoles,  J. Chem.  Phys., 107, 
481-492 (1997)

The parameters  distributed with TINKER are  modified values 
based  on the  work of  Pengyu Ren  starting from  the Ph.D. 
thesis of  Yong Kong, ``Multipole Electrostatic  Methods for 
Protein   Modeling   with    Reaction   Field   Treatment'', 
Biochemistry & Molecular  Biophysics, Washington University, 
St. Louis, August, 1997
 7.     Use of the Keyword Control File

     This  section contains  a  description  of the  keyword 
parameters which may  be used to define or  alter the course 
of  a  TINKER  calculation.  The  keyword  control  file  is 
optional in the  sense that all of the  TINKER programs will 
run in the absence of a  keyfile and will simply use default 
values or  query the  user for needed  information. However, 
the keywords allow use of  a wide variety of algorithmic and 
procedural   options,   many   of  which   are   unavailable 
interactively.

     Keywords are  read from  the keyword control  file. All 
programs look first for a keyfile with the same base name as 
the input molecular system and ending in the extension .key. 
If  this file does  not exist,  then TINKER  tries to  use a 
generic keyfile with the name  tinker.key and located in the 
same  directory as  the input  system. If  neither a  system 
specific  nor  a generic  keyfile  is  present, TINKER  will 
continue  by using  default values  for keyword  options and 
asking interactive questions as necessary.

     TINKER  searches the  keyfile  during the  course of  a 
calculation for  relevant keywords that may  be present. All 
keywords  must appear  as the  first word  on the  line. Any 
blank space to  the left of the keyword is  ignored, and all 
contents of the keyfiles are case insensitive. Some keywords 
take modifiers; i.e., TINKER looks  further on the same line 
for  additional  information,  such  as the  value  of  some 
parameter related  to the  keyword. Modifier  information is 
read in free format, but must be completely contained on the 
same line  as the original  keyword. Any lines  contained in 
the keyfile which do not  qualify as valid keyword lines are 
treated as comments and are simply ignored.

     Several keywords  take a  list of integer  values (atom 
numbers, for  example) as modifiers. For  these keywords the 
integers can  simply be  listed explicitly and  separated by 
spaces, commas or tabs. If a range of numbers is desired, it 
can be specified by listing the negative of the first number 
of the range, followed by a separator and the last number of 
the range. For  example, the keyword line ACTIVE 4  -9 17 23 
could be used  to add atoms 4,  9 through 17, and  23 to the 
set of active atoms during a TINKER calculation.

     Listed below are the  valid TINKER keywords sorted into 
groups  by  general  function.  The  section  ends  with  an 
alphabetical listing  of the individual keywords  along with 
brief descriptions  of their action and  possible modifiers, 
and examples of usage.


Keywords Grouped by Functionality

OUTPUT CONTROL KEYWORDS

ARCHIVE               DEBUG                 DIGITS
ECHO                  EXIT-PAUSE            NOVERSION  
OVERWRITE             PRINTOUT              SAVE-CYCLE
SAVE-INDUCED          SAVE-VELOCITY         VERBOSE    
WRITEOUT              

FORCE FIELD SELECTION KEYWORDS

FORCEFIELD            PARAMETERS

POTENTIAL FUNCTION SELECTION KEYWORDS

ANGANGTERM            ANGLETERM             BONDTERM
CHARGETERM            CHGDPLTERM            DIPOLETERM
EXTRATERM             IMPROPTERM            IMPTORSTERM
METALTERM             MPOLETERM             OPBENDTERM 
OPDISTTERM            POLARIZETERM          RESTRAINTERM    
RXNFIELDTERM          SOLVATETERM           STRBNDTERM 
STRTORTERM            TORSIONTERM           TORTORTERM 
UREYTERM              VDWTERM
                      
POTENTIAL FUNCTION PARAMETER KEYWORDS

ANGANG                ANGLE                 ANGLE3
ANGLE4                ANGLE5                ANGLEF
ATOM                  BIOTYPE               BOND
BOND3                 BOND4                 BOND5
CHARGE                DIPOLE                DIPOLE3
DIPOLE4               DIPOLE5               ELECTNEG
HBOND                 IMPROPER              IMPTORS    METAL
MULTIPOLE             OPBEND
OPDIST                PIATOM                PIBOND
POLARIZE              SOLVATE               STRBND
STRTORS               TORSION               TORSION4   
TORSION5              UREYBRAD              VDW
VDW14                 VDWPR

ENERGY UNIT CONVERSION KEYWORDS

ANGLEUNIT             ANGANGUNIT            BONDUNIT
IMPROPUNIT            IMPTORUNIT            OPBENDUNIT 
OPDISTUNIT            STRBNDUNIT            STRTORUNIT 
TORSIONUNIT           UREYUNIT

LOCAL GEOMETRY FUNCTIONAL FORM KEYWORDS

ANGLE-CUBIC           ANGLE-QUARTIC         ANGLE-PENTIC
ANGLE-SEXTIC          BOND-CUBIC            BOND-QUARTIC    
BONDTYPE              MM2-STRBND            PISYSTEM
UREY-CUBIC            UREY-QUARTIC

VAN DER WAALS FUNCTIONAL FORM KEYWORDS

A-EXPTERM             B-EXPTERM             C-EXPTERM
DELTA-HALGREN         EPSILONRULE           GAMMA-HALGREN   
GAUSSTYPE             RADIUSRULE            RADIUSSIZE 
RADIUSTYPE            VDW-12-SCALE          VDW-13-SCALE
VDW-14-SCALE          VDW-15-SCALE          VDWTYPE

ELECTROSTATICS FUNCTIONAL FORM KEYWORDS

CHG-12-SCALE          CHG-13-SCALE          CHG-14-SCALE
CHG-15-SCALE          DIELECTRIC            DIRECT-11-SCALE
DIRECT-12-SCALE       DIRECT-13-SCALE       DIRECT-14-SCALE
MUTUAL-11-SCALE       MUTUAL-12-SCALE       MUTUAL-13-SCALE
MUTUAL-14-SCALE       POLAR-11-SCALE        POLAR-12-SCALE
POLAR-13-SCALE        POLAR-14-SCALE        POLAR-DAMP 
POLAR-EPS             POLAR-OLD             POLAR-SOR
POLARIZATION          REACTIONFIELD

NONBONDED CUTOFF KEYWORDS

CHG-CUTOFF            CHG-TAPER             CUTOFF
DPL-CUTOFF            DPL-TAPER             HESS-CUTOFF
LIGHTS                MPOLE-CUTOFF          MPOLE-TAPER
NEIGHBOR-GROUPS       NEUTRAL-GROUPS        POLYMER-CUTOFF
TAPER                 TRUNCATE              VDW-CUTOFF
VDW-TAPER

EWALD SUMMATION KEYWORDS

EWALD                 EWALD-ALPHA           EWALD-BOUNDARY  
EWALD-CUTOFF          EWALD-FRACTION        PME-GRID
PME-ORDER

CRYSTAL LATTICE & PERIODIC BOUNDARY KEYWORDS

A-AXIS                B-AXIS                C-AXIS
ALPHA                 BETA                  GAMMA
OCTAHEDRON            SPACEGROUP

OPTIMIZATION KEYWORDS

ANGMAX                CAPPA                 FCTMIN
HGUESS                INTMAX                LBFGS-VECTORS   
MAXITER               NEWHESS               NEXTITER   
STEPMAX               STPMIN

DYNAMICS KEYWORDS

COLLISION             COMPRESS              FRICTION   
FRICTION-SCALING      INTEGRATE             TAU-PRESSURE    
TAU-TEMPERATURE       THERMOSTAT

TRANSITION STATE KEYWORDS

DIVERGE               GAMMAMIN              REDUCE
SADDLEPOINT

DISTANCE GEOMETRY KEYWORDS

TRIAL-DISTANCE        TRIAL-DISTRIBUTION

RANDOM NUMBER KEYWORDS

RANDOMSEED

FREE ENERGY PERTURBATION KEYWORDS

LAMBDA                MUTATE

PARTIAL STRUCTURE KEYWORDS

ACTIVE                GROUP                 GROUP-INTER
GROUP-INTRA           GROUP-MOLECULE        GROUP-SELECT    
INACTIVE

CONSTRAINT & RESTRAINT KEYWORDS

BASIN                 RATTLE                RATTLE-BOND
RESTRAIN-DIHEDRAL     RESTRAIN-DISTANCE     RESTRAIN-
POSITION
SPHERE                WALL

POTENTIAL SMOOTHING KEYWORDS

DEFORM                DIFFUSE-CHARGE        DIFFUSE-TORSION
DIFFUSE-VDW


Description of Individual Keywords

The following is an alphabetical list of the TINKER keywords 
along with a brief description of the action of each keyword 
and  required or  optional parameters  that can  be used  to 
extend  or  modify  each   keyword.  The  form  of  possible 
modifiers,  if  any, is  shown  in  brackets following  each 
keyword.

A-AXIS [real]     Sets the value  of the a-axis length for a 
crystal unit cell, or,  equivalently,  the X-axis length for 
a  periodic box.  The length  value in  Angstroms is  listed 
after the keyword.

A-EXPTERM   [real]      Sets   the   value   of  the   ``A'' 
premultiplier term in the Buckingham van der Waals function, 
i.e., the  value of  A in  the formula  Evdw =  e {  A exp[-
B(Ro/R)] - C (Ro/R)6 }.

ACTIVE  [integer list]      Sets  the list  of active  atoms 
during  a TINKER  computation.  Individual potential  energy 
terms are  computed when at  least one atom involved  in the 
term  is active.  For Cartesian  space calculations,  active 
atoms  are  those  allowed  to  move.  For  torsional  space 
calculations, rotations  are allowed  when all atoms  on one 
side of the  rotated bond are active.  Multiple ACTIVE lines 
can be present in the  keyfile and are treated cumulatively.  
On each line the keyword can be followed by one or more atom 
numbers or atom  ranges. The presence of  any ACTIVE keyword 
overrides any INACTIVE keywords in the keyfile.

ALPHA [real]     Sets the value of  the a angle of a crystal 
unit cell, i.e., the angle  between the b-axis and c-axis of 
a unit cell, or, equivalently,  the angle between the Y-axis 
and  Z-axis of  a periodic  box.  The default  value in  the 
absence of the ALPHA keyword is 90 degrees.

ANGANG [1 integer  & 3 reals]     This  keyword provides the 
values  for  a  single   angle-angle  cross  term  potential 
parameter.

ANGANGTERM [NONE/ONLY]     This keyword  controls use of the 
angle-angle cross term potential energy. In the absence of a 
modifying  option,   this  keyword  turns  on   use  of  the 
potential. The NONE  option turns off use  of this potential 
energy term. The ONLY option  turns off all potential energy 
terms except for this one.

ANGANGUNIT  [real]      Sets  the  scale  factor  needed  to 
convert the  energy value computed by  the angle-angle cross 
term potential into units of kcal/mole. The correct value is 
force field  dependent and typically provided  in the header 
of the  master force  field parameter  file. The  default of 
(p/180)2 = 0.0003046  is used, if the  ANGANGUNIT keyword is 
not given in the force field parameter file or the keyfile.

ANGLE [3 integers  & 4 reals]     This  keyword provides the 
values  for  a  single  bond angle  bending  parameter.  The 
integer modifiers give the atom  class numbers for the three 
kinds of atoms involved in the angle which is to be defined. 
The real number modifiers give  the force constant value for 
the angle and  up to three ideal bond angles  in degrees. In 
most  cases only  one ideal  bond angle  is given,  and that 
value  is used  for all  occurrences of  the specified  bond 
angle. If all three ideal angles are given, the values apply 
when the central atom of the  angle is attached to 0, 1 or 2 
additional  hydrogen  atoms, respectively.  This  ``hydrogen 
environment''   option   is   provided  to   implement   the 
corresponding  feature of  Allinger's MM  force fields.  The 
default units for the  force constant are kcal/mole/radian2, 
but this can be controlled via the ANGLEUNIT keyword.

ANGLE-CUBIC [real]     Sets  the value of the  cubic term in 
the Taylor series  expansion form of the  bond angle bending 
potential energy.  The real number modifier  gives the value 
of  the   coefficient  as   a  multiple  of   the  quadratic 
coefficient.  This  term  multiplied by  the  angle  bending 
energy unit  conversion factor, the force  constant, and the 
cube of the deviation of the bond angle from its ideal value 
gives the  cubic contribution  to the angle  bending energy. 
The default value in the  absence of the ANGLE-CUBIC keyword 
is zero; i.e., the cubic angle bending term is omitted.

ANGLE-PENTIC [real]      Sets the  value of the  fifth power 
term in the  Taylor series expansion form of  the bond angle 
bending potential energy. The real number modifier gives the 
value  of the  coefficient as  a multiple  of the  quadratic 
coefficient.  This  term  multiplied by  the  angle  bending 
energy unit  conversion factor, the force  constant, and the 
fifth  power of  the deviation  of the  bond angle  from its 
ideal  value  gives the  pentic  contribution  to the  angle 
bending  energy. The  default value  in the  absence of  the 
ANGLE-PENTIC keyword is zero; i.e., the pentic angle bending 
term is omitted.

ANGLE-QUARTIC [real]     Sets the  value of the quartic term 
in  the  Taylor series  expansion  form  of the  bond  angle 
bending potential energy. The real number modifier gives the 
value  of the  coefficient as  a multiple  of the  quadratic 
coefficient.  This  term  multiplied by  the  angle  bending 
energy unit  conversion factor, the force  constant, and the 
forth  power of  the deviation  of the  bond angle  from its 
ideal  value gives  the  quartic contribution  to the  angle 
bending  energy. The  default value  in the  absence of  the 
ANGLE-QUARTIC  keyword  is  zero; i.e.,  the  quartic  angle 
bending term is omitted.

ANGLE-SEXTIC [real]      Sets the  value of the  sixth power 
term in the  Taylor series expansion form of  the bond angle 
bending potential energy. The real number modifier gives the 
value  of the  coefficient as  a multiple  of the  quadratic 
coefficient.  This  term  multiplied by  the  angle  bending 
energy unit  conversion factor, the force  constant, and the 
sixth  power of  the deviation  of the  bond angle  from its 
ideal  value  gives the  sextic  contribution  to the  angle 
bending  energy. The  default value  in the  absence of  the 
ANGLE-SEXTIC keyword is zero; i.e., the sextic angle bending 
term is omitted.

ANGLE3 [3 integers & 4  reals]     This keyword provides the 
values for a single bond angle bending parameter specific to 
atoms in  3-membered rings.  The integer modifiers  give the 
atom class numbers for the  three kinds of atoms involved in 
the angle which is to  be defined. The real number modifiers 
give the force constant value for  the angle and up to three 
ideal bond angles in degrees.  If all three ideal angles are 
given, the values  apply when the central atom  of the angle 
is  attached  to  0,  1  or  2  additional  hydrogen  atoms, 
respectively. The  default units for the  force constant are 
kcal/mole/radian2,  but  this  can  be  controlled  via  the 
ANGLEUNIT  keyword.  If  any ANGLE3  keywords  are  present, 
either  in the  master  force field  parameter  file or  the 
keyfile, then TINKER requires that special ANGLE3 parameters 
be given for all angles  in 3-membered rings. In the absence 
of any  ANGLE3 keywords,  standard ANGLE parameters  will be 
used for bonds in 3-membered rings.

ANGLE4 [3 integers & 4  reals]     This keyword provides the 
values for a single bond angle bending parameter specific to 
atoms in  4-membered rings.  The integer modifiers  give the 
atom class numbers for the  three kinds of atoms involved in 
the angle which is to  be defined. The real number modifiers 
give the force constant value for  the angle and up to three 
ideal bond angles in degrees.  If all three ideal angles are 
given, the values  apply when the central atom  of the angle 
is  attached  to  0,  1  or  2  additional  hydrogen  atoms, 
respectively. The  default units for the  force constant are 
kcal/mole/radian2,  but  this  can  be  controlled  via  the 
ANGLEUNIT  keyword.  If  any ANGLE4  keywords  are  present, 
either  in the  master  force field  parameter  file or  the 
keyfile, then TINKER requires that special ANGLE4 parameters 
be given for all angles  in 4-membered rings. In the absence 
of any  ANGLE4 keywords,  standard ANGLE parameters  will be 
used for bonds in 4-membered rings.

ANGLE5 [3 integers & 4  reals]     This keyword provides the 
values for a single bond angle bending parameter specific to 
atoms in  5-membered rings.  The integer modifiers  give the 
atom class numbers for the  three kinds of atoms involved in 
the angle which is to  be defined. The real number modifiers 
give the force constant value for  the angle and up to three 
ideal bond angles in degrees.  If all three ideal angles are 
given, the values  apply when the central atom  of the angle 
is  attached  to  0,  1  or  2  additional  hydrogen  atoms, 
respectively. The  default units for the  force constant are 
kcal/mole/radian2,  but  this  can  be  controlled  via  the 
ANGLEUNIT  keyword.  If  any ANGLE5  keywords  are  present, 
either  in the  master  force field  parameter  file or  the 
keyfile, then TINKER requires that special ANGLE5 parameters 
be given for all angles  in 5-membered rings. In the absence 
of any  ANGLE5 keywords,  standard ANGLE parameters  will be 
used for bonds in 5-membered rings.

ANGLEF [3 integers & 3  reals]     This keyword provides the 
values  for a  single  bond angle  bending  parameter for  a 
SHAPES-style   Fourier  potential   function.  The   integer 
modifiers give the atom class numbers for the three kinds of 
atoms involved in the angle which is to be defined. The real 
number  modifiers  give the  force  constant  value for  the 
angle,  the  angle shift  in  degrees,  and the  periodicity 
value. Note that  the force constant should be  given as the 
``harmonic''  value and  not the  native Fourier  value. The 
default units for the  force constant are kcal/mole/radian2, 
but this can be controlled via the ANGLEUNIT keyword.

ANGLETERM [NONE/ONLY]      This keyword controls use  of the 
bond angle bending potential energy  term. In the absence of 
a  modifying  option,  this  keyword turns  on  use  of  the 
potential. The NONE  option turns off use  of this potential 
energy term. The ONLY option  turns off all potential energy 
terms except for this one.

ANGLEUNIT [real]     Sets the scale factor needed to convert 
the  energy  value  computed   by  the  bond  angle  bending 
potential  into units  of  kcal/mole. The  correct value  is 
force field  dependent and typically provided  in the header 
of the master force field  parameter file. The default value 
of (p/180)2 = 0.0003046 is used, if the ANGLEUNIT keyword is 
not given in the force field parameter file or the keyfile.

ANGMAX [real]     Set the  maximum permissible angle between 
the current  optimization search direction and  the negative 
of the  gradient direction. If  this maximum angle  value is 
exceeded,  the  optimization  routine  will  note  an  error 
condition  and   may  restart  from  the   steepest  descent 
direction. The  default value in  the absence of  the ANGMAX 
keyword is usually 88 degrees for conjugate gradient methods 
and  180  degrees  (i.e.,   disabled)  for  variable  metric 
optimizations.

ARCHIVE     Causes TINKER  molecular dynamics-based programs 
to  write  trajectories  directly  to  a  single  plain-text 
archive  file  with the  .arc  format.  If an  archive  file 
already exists  at the  start of  the calculation,  then the 
newly generated  trajectory is  appended to  the end  of the 
existing file. The default in the absence of this keyword is 
to write the trajectory  snapshots to consecutively numbered 
cycle files.

ATOM  [2  integers, name,  quoted  string,  integer, real  & 
integer]      This keyword  provides  the  values needed  to 
define a single force field atom type.

B-AXIS [real]     Sets the value  of the b-axis length for a 
crystal unit cell, or,  equivalently,  the Y-axis length for 
a  periodic box.  The length  value in  Angstroms is  listed 
after  the keyword.  If the  keyword is  absent, the  b-axis 
length is set equal to the a-axis length.

B-EXPTERM [real]     Sets the value of the ``B'' exponential 
factor in the  Buckingham van der Waals  function, i.e., the 
value of  B in the  formula Evdw =  e { A exp[-B(Ro/R)]  - C 
(Ro/R)6 }.

BASIN  [2 reals]      Presence of  this keyword  turns on  a 
``basin'' restraint potential function  that serves to drive 
the system  toward a compact structure.  The actual function 
is a  Gaussian of the form  Ebasin = S A  exp[-B R2], summed 
over  all pairs  of atoms  where R  is the  distance between 
atoms. The A and B values are the depth and width parameters 
given as modifiers  to the BASIN keyword.  This potential is 
currently  used to  control the  degree of  expansion during 
potential  energy  smooth  procedures  through  the  use  of 
shallow, broad basins.

BETA [real]     Sets  the value of the b angle  of a crystal 
unit cell, i.e., the angle  between the a-axis and c-axis of 
a unit cell, or, equivalently,  the angle between the X-axis 
and  Z-axis of  a periodic  box.  The default  value in  the 
absence of the  BETA keyword is to set the  b angle equal to 
the a angle as given by the keyword ALPHA.

BIOTYPE [integer,  name, quoted  string &  integer]     This 
keyword  provides the  values to  define the  correspondence 
between a  single biopolymer atom  type and its  force field 
atom type.

BOND [2  integers & 2  reals]     This keyword  provides the 
values for  a single bond stretching  parameter. The integer 
modifiers give the  atom class numbers for the  two kinds of 
atoms involved in the bond which  is to be defined. The real 
number modifiers give the force  constant value for the bond 
and the  ideal bond length in  Å. The default units  for the 
force constant are kcal/mole/Å2,  but this can be controlled 
via the BONDUNIT keyword.

BOND-CUBIC [real]      Sets the value  of the cubic  term in 
the  Taylor series  expansion  form of  the bond  stretching 
potential energy.  The real number modifier  gives the value 
of  the   coefficient  as   a  multiple  of   the  quadratic 
coefficient.  This term  multiplied by  the bond  stretching 
energy unit  conversion factor, the force  constant, and the 
cube  of the  deviation of  the bond  length from  its ideal 
value gives  the cubic  contribution to the  bond stretching 
energy. The default  value in the absence  of the BOND-CUBIC 
keyword is  zero; i.e.,  the cubic  bond stretching  term is 
omitted.

BOND-QUARTIC [real]      Sets the value of  the quartic term 
in the Taylor  series expansion form of  the bond stretching 
potential energy.  The real number modifier  gives the value 
of  the   coefficient  as   a  multiple  of   the  quadratic 
coefficient.  This term  multiplied by  the bond  stretching 
energy unit  conversion factor, the force  constant, and the 
forth power  of the  deviation of the  bond length  from its 
ideal  value  gives the  quartic  contribution  to the  bond 
stretching energy. The  default value in the  absence of the 
BOND-QUARTIC  keyword  is  zero;   i.e.,  the  quartic  bond 
stretching term is omitted.

BOND3 [2 integers  & 2 reals]     This  keyword provides the 
values for  a single  bond stretching parameter  specific to 
atoms in  3-membered rings.  The integer modifiers  give the 
atom class  numbers for the  two kinds of atoms  involved in 
the bond which  is to be defined. The  real number modifiers 
give the  force constant  value for the  bond and  the ideal 
bond length in  Å. The default units for  the force constant 
are  kcal/mole/Å2,  but  this  can  be  controlled  via  the 
BONDUNIT keyword. If any  BOND3 keywords are present, either 
in the  master force  field parameter  file or  the keyfile, 
then TINKER requires that  special BOND3 parameters be given 
for all  bonds in  3-membered rings. In  the absence  of any 
BOND3 keywords,  standard BOND  parameters will be  used for 
bonds in 3-membered rings.

BOND4 [2 integers  & 2 reals]     This  keyword provides the 
values for  a single  bond stretching parameter  specific to 
atoms in  4-membered rings.  The integer modifiers  give the 
atom class  numbers for the  two kinds of atoms  involved in 
the bond which  is to be defined. The  real number modifiers 
give the  force constant  value for the  bond and  the ideal 
bond length in  Å. The default units for  the force constant 
are  kcal/mole/Å2,  but  this  can  be  controlled  via  the 
BONDUNIT keyword. If any  BOND4 keywords are present, either 
in the  master force  field parameter  file or  the keyfile, 
then TINKER requires that  special BOND4 parameters be given 
for all  bonds in  4-membered rings. In  the absence  of any 
BOND4 keywords,  standard BOND  parameters will be  used for 
bonds in 4-membered rings

BOND5 [2 integers  & 2 reals]     This  keyword provides the 
values for  a single  bond stretching parameter  specific to 
atoms in  5-membered rings.  The integer modifiers  give the 
atom class  numbers for the  two kinds of atoms  involved in 
the bond which  is to be defined. The  real number modifiers 
give the  force constant  value for the  bond and  the ideal 
bond length in  Å. The default units for  the force constant 
are  kcal/mole/Å2,  but  this  can  be  controlled  via  the 
BONDUNIT keyword. If any  BOND5 keywords are present, either 
in the  master force  field parameter  file or  the keyfile, 
then TINKER requires that  special BOND5 parameters be given 
for all  bonds in  5-membered rings. In  the absence  of any 
BOND5 keywords,  standard BOND  parameters will be  used for 
bonds in 5-membered rings

BONDTERM [NONE/ONLY]      This keyword  controls use  of the 
bond stretching potential  energy term. In the  absence of a 
modifying  option,   this  keyword  turns  on   use  of  the 
potential. The NONE  option turns off use  of this potential 
energy term. The ONLY option  turns off all potential energy 
terms except for this one.

BONDTYPE [TAYLOR/MORSE/GAUSSIAN]      Chooses the functional 
form  of the  bond stretching  potential. The  TAYLOR option 
selects  a Taylor  series  expansion  containing terms  from 
harmonic through  quartic. The MORSE option  selects a Morse 
potential fit to the ideal  bond length and stretching force 
constant  parameter  values.  The GAUSSIAN  option  uses  an 
inverted  Gaussian with  amplitude equal  to the  Morse bond 
dissociation  energy   and  width   set  to   reproduce  the 
vibrational frequency  of a harmonic potential.  The default 
is to use the TAYLOR potential.

BONDUNIT [real]     Sets the  scale factor needed to convert 
the energy  value computed by the  bond stretching potential 
into units  of kcal/mole. The  correct value is  force field 
dependent and typically provided in the header of the master 
force  field parameter  file. The  default value  of 1.0  is 
used,  if the  BONDUNIT keyword  is not  given in  the force 
field parameter file or the keyfile.

C-AXIS [real]     Sets the value  of the C-axis length for a 
crystal unit cell, or,  equivalently,  the Z-axis length for 
a  periodic box.  The length  value in  Angstroms is  listed 
after  the keyword.  If the  keyword is  absent, the  C-axis 
length is set equal to the A-axis length.

C-EXPTERM [real]     Sets the  value of the ``C'' dispersion 
multiplier in  the Buckingham van der  Waals function, i.e., 
the value of C in the formula Evdw = e { A exp[-B(Ro/R)] - C 
(Ro/R)6 }.

CAPPA  [real]     This  keyword is  used to  set the  normal 
termination criterion  for the  line search phase  of TINKER 
optimization routines. The line search exits successfully if 
the ratio of the current  gradient projection on the line to 
the projection at  the start of the line  search falls below 
the value  of CAPPA. A default  value of 0.1 is  used in the 
absence of the CAPPA keyword.

CHARGE  [1 integer  & 1  real]     This  keyword provides  a 
value  for  a  single atomic  partial  charge  electrostatic 
parameter. The integer modifier, if positive, gives the atom 
type number for which the charge parameter is to be defined. 
Note that vdw parameters are  given for atom types, not atom 
classes.  If  the integer  modifier  is  negative, then  the 
parameter  value to  follow applies  only to  the individual 
atom whose atom number is  the negative of the modifier. The 
real number modifier gives the  values of the atomic partial 
charge in electrons.

CHARGETERM [NONE/ONLY]     This keyword  controls use of the 
charge-charge potential energy term  between pairs of atomic 
partial charges. In the absence  of a modifying option, this 
keyword turns on use of the potential. The NONE option turns 
off use of this potential energy term. The ONLY option turns 
off all potential energy terms except for this one.

CHG-12-SCALE    [real]       This    keyword   provides    a 
multiplicative scale factor that is applied to charge-charge 
electrostatic  interactions  between  1-2  connected  atoms, 
i.e., atoms that  are directly bonded. The  default value of 
0.0 is  used, if  the CHG-12-SCALE keyword  is not  given in 
either the parameter file or the keyfile.

CHG-13-SCALE    [real]       This    keyword   provides    a 
multiplicative scale factor that is applied to charge-charge 
electrostatic  interactions  between  1-3  connected  atoms, 
i.e.,  atoms separated  by two  covalent bonds.  The default 
value of  0.0 is  used, if the  CHG-13-SCALE keyword  is not 
given in either the parameter file or the keyfile.

CHG-14-SCALE    [real]       This    keyword   provides    a 
multiplicative scale factor that is applied to charge-charge 
electrostatic  interactions  between  1-4  connected  atoms, 
i.e., atoms  separated by three covalent  bonds. The default 
value of  1.0 is  used, if the  CHG-14-SCALE keyword  is not 
given in either the parameter file or the keyfile.

CHG-15-SCALE    [real]       This    keyword   provides    a 
multiplicative scale factor that is applied to charge-charge 
electrostatic  interactions  between  1-5  connected  atoms, 
i.e., atoms  separated by  four covalent bonds.  The default 
value of  1.0 is  used, if the  CHG-15-SCALE keyword  is not 
given in either the parameter file or the keyfile.

CHG-CUTOFF  [real]     Sets  the  cutoff  distance value  in 
Angstroms for  charge-charge electrostatic  potential energy 
interactions. The  energy for any  pair of sites  beyond the 
cutoff distance will  be set to zero. Other  keywords can be 
used to select a smoothing  scheme near the cutoff distance. 
The default cutoff distance in the absence of the CHG-CUTOFF 
keyword  is infinite  for  nonperiodic systems  and 9.0  for 
periodic systems.

CHG-TAPER [real]     This keyword allows modification of the 
cutoff  window  for  charge-charge  electrostatic  potential 
energy interactions. It is similar in form and action to the 
TAPER keyword,  except that  its value  applies only  to the 
charge-charge potential. The default value in the absence of 
the CHG-TAPER keyword is to  begin the cutoff window at 0.65 
of the corresponding cutoff distance.

CHGDPLTERM [NONE/ONLY]     This keyword  controls use of the 
charge-dipole potential  energy term between  atomic partial 
charges  and bond  dipoles. In  the absence  of a  modifying 
option, this keyword turns on use of the potential. The NONE 
option turns off use of this potential energy term. The ONLY 
option turns off all potential  energy terms except for this 
one.

COLLISION [real]     Sets the  value of the random collision 
frequency used in the Andersen stochastic collision dynamics 
thermostat. The supplied value has  units of fs-1 atom-1 and 
is multiplied internal to TINKER by  the time step in fs and 
N-2/3 where N is the number of atoms. The default value used 
in  the absence  of the  COLLISION keyword  is 0.1  which is 
appropriate  for many  systems  but may  need adjustment  to 
achieve adequate temperature  control without perturbing the 
dynamics.

COMPRESS  [real]      Sets the  value  of  the bulk  solvent 
isothermal compressibility in Atm-1  for use during pressure 
computation and scaling  in molecular dynamics computations. 
The  default  value used  in  the  absence of  the  COMPRESS 
keyword is  0.000046, appropriate for water.  This parameter 
serves as  a scale  factor for the  Groningen-style pressure 
bath coupling  time, and  its exact value  should not  be of 
critical importance.

CUTOFF  [real]     Sets  the cutoff  distance value  for all 
nonbonded potential energy interactions.  The energy for any 
of the  nonbonded potentials of  a pair of sites  beyond the 
cutoff distance will  be set to zero. Other  keywords can be 
used to select a smoothing  scheme near the cutoff distance, 
or to apply different  cutoff distances to various nonbonded 
energy terms.

DEBUG      Turns on  printing  of  detailed information  and 
intermediate  values throughout  the  progress  of a  TINKER 
computation; not  recommended for use with  large structures 
or full potential energy functions  since a summary of every 
individual interaction will usually be output.

DEFORM  [real]     Sets  the amount  of diffusion  equation-
style smoothing that will be applied to the potential energy 
surface when using  the SMOOTH force field.  The real number 
option is equivalent  to the ``time'' value  in the original 
Piela, et al.  formalism; the larger the  value, the greater 
the smoothing.  The default value  is zero, meaning  that no 
smoothing will be applied.

DELTA-HALGREN [real]      Sets the value of  the d parameter 
in Halgren's  buffered 14-7 vdw potential  energy functional 
form. In the absence of the DELTA-HALGREN keyword, a default 
value of 0.07 is used.

DIELECTRIC [real]     Sets the  value of the bulk dielectric 
constant used to damp all electrostatic interaction energies 
for any of the TINKER electrostatic potential functions. The 
default value is force field dependent, but is usually equal 
to 1.0 (for Allinger's MM force fields the default is 1.5).
 
DIFFUSE-CHARGE  [real]      This   keyword  is  used  during 
potential  function  smoothing  procedures  to  specify  the 
effective  diffusion  coefficient  to   be  applied  to  the 
smoothed form  of the Coulomb's Law  charge-charge potential 
function. In  the absence  of the DIFFUSE-CHARGE  keyword, a 
default value of 3.5 is used.
 
DIFFUSE-TORSION  [real]      This  keyword  is  used  during 
potential  function  smoothing  procedures  to  specify  the 
effective  diffusion  coefficient  to   be  applied  to  the 
smoothed form  of the  torsion angle potential  function. In 
the absence of the  DIFFUSE-TORSION keyword, a default value 
of 0.0225 is used.

DIFFUSE-VDW [real]     This keyword is used during potential 
function  smoothing  procedures  to  specify  the  effective 
diffusion coefficient to be applied to the smoothed Gaussian 
approximation to  the Lennard-Jones van der  Waals potential 
function.  In  the absence  of  the  DIFFUSE-VDW keyword,  a 
default value of 1.0 is used.

DIGITS  [integer]     This  keyword controls  the number  of 
digits of precision  output by TINKER in reporting potential 
energies and atomic coordinates.  The allowed values for the 
integer modifier  are 4, 6 and  8. Input values less  than 4 
will be set to 4, and those greater than 8 will be set to 8. 
Final energy  values reported  by most TINKER  programs will 
contain the specified  number of digits to the  right of the 
decimal point. The number of decimal places to be output for 
atomic coordinates is generally two larger than the value of 
DIGITS. In the absence of the DIGITS keyword a default value 
of 4  is used, and  energies  will be reported to  4 decimal 
places with coordinates to 6 decimal places.

DIPOLE [2 integers & 2  reals]     This keyword provides the 
values for a single bond dipole electrostatic parameter. The 
integer modifiers  give the  atom type  numbers for  the two 
kinds of  atoms involved in the  bond dipole which is  to be 
defined. The  real number  modifiers give  the value  of the 
bond dipole  in Debyes and  the position of the  dipole site 
along the bond.  If the bond dipole value  is positive, then 
the first of  the two atom types is the  positive end of the 
dipole. For  a negative  bond dipole  value, the  first atom 
type listed is  negative. The position along the  bond is an 
optional modifier that gives the  postion of the dipole site 
as a fraction  between the first atom  type (position=0) and 
the  second  atom type  (position=1).  The  default for  the 
dipole position in the absence  of a specified value is 0.5, 
placing the dipole at the midpoint of the bond.

DIPOLE3 [2 integers & 2 reals]     This keyword provides the 
values  for a  single  bond  dipole electrostatic  parameter 
specific to atoms in 3-membered rings. The integer modifiers 
give  the atom  type  numbers  for the  two  kinds of  atoms 
involved in the bond dipole which is to be defined. The real 
number modifiers give the value of the bond dipole in Debyes 
and  the position  of the  dipole site  along the  bond. The 
default  for  the  dipole  position  in  the  absence  of  a 
specified value is  0.5, placing the dipole  at the midpoint 
of the bond. If any  DIPOLE3 keywords are present, either in 
the master force  field parameter file or  the keyfile, then 
TINKER requires that special DIPOLE3 parameters be given for 
all bond dipoles in 3-membered  rings. In the absence of any 
DIPOLE3 keywords,  standard DIPOLE  parameters will  be used 
for bonds in 3-membered rings.

DIPOLE4 [2 integers & 2 reals]     This keyword provides the 
values  for a  single  bond  dipole electrostatic  parameter 
specific to atoms in 4-membered rings. The integer modifiers 
give  the atom  type  numbers  for the  two  kinds of  atoms 
involved in the bond dipole which is to be defined. The real 
number modifiers give the value of the bond dipole in Debyes 
and  the position  of the  dipole site  along the  bond. The 
default  for  the  dipole  position  in  the  absence  of  a 
specified value is  0.5, placing the dipole  at the midpoint 
of the bond. If any  DIPOLE4 keywords are present, either in 
the master force  field parameter file or  the keyfile, then 
TINKER requires that special DIPOLE4 parameters be given for 
all bond dipoles in 4-membered  rings. In the absence of any 
DIPOLE4 keywords,  standard DIPOLE  parameters will  be used 
for bonds in 4-membered rings.

DIPOLE5 [2 integers & 2 reals]     This keyword provides the 
values  for a  single  bond  dipole electrostatic  parameter 
specific to atoms in 5-membered rings. The integer modifiers 
give  the atom  type  numbers  for the  two  kinds of  atoms 
involved in the bond dipole which is to be defined. The real 
number modifiers give the value of the bond dipole in Debyes 
and  the position  of the  dipole site  along the  bond. The 
default  for  the  dipole  position  in  the  absence  of  a 
specified value is  0.5, placing the dipole  at the midpoint 
of the bond. If any  DIPOLE5 keywords are present, either in 
the master force  field parameter file or  the keyfile, then 
TINKER requires that special DIPOLE5 parameters be given for 
all bond dipoles in 5-membered  rings. In the absence of any 
DIPOLE5 keywords,  standard DIPOLE  parameters will  be used 
for bonds in 5-membered rings.

DIPOLETERM [NONE/ONLY]     This keyword  controls use of the 
dipole-dipole potential  energy term  between pairs  of bond 
dipoles. In the absence of  a modifying option, this keyword 
turns on use of the potential. The NONE option turns off use 
of this potential energy term. The ONLY option turns off all 
potential energy terms except for this one.

DIRECT-11-SCALE   [real]       This   keyword   provides   a 
multiplicative scale factor that is applied to the permanent 
(direct)  field due  to  atoms within  a polarization  group 
during an  induced dipole calculation, i.e.,  atoms that are 
in the same polarization group  as the atom being polarized. 
The default  value of  0.0 is  used, if  the DIRECT-11-SCALE 
keyword is  not given  in either the  parameter file  or the 
keyfile.

DIRECT-12-SCALE   [real]       This   keyword   provides   a 
multiplicative scale factor that is applied to the permanent 
(direct)  field  due to  atoms  in  1-2 polarization  groups 
during an  induced dipole calculation, i.e.,  atoms that are 
in  polarization  groups  directly connected  to  the  group 
containing the  atom being  polarized. The default  value of 
0.0 is used, if the  DIRECT-12-SCALE keyword is not given in 
either the parameter file or the keyfile.

DIRECT-13-SCALE   [real]       This   keyword   provides   a 
multiplicative scale factor that is applied to the permanent 
(direct)  field  due to  atoms  in  1-3 polarization  groups 
during an  induced dipole calculation, i.e.,  atoms that are 
in polarization groups separated by one group from the group 
containing the  atom being  polarized. The default  value of 
0.0 is used, if the  DIRECT-13-SCALE keyword is not given in 
either the parameter file or the keyfile.

DIRECT-14-SCALE   [real]       This   keyword   provides   a 
multiplicative scale factor that is applied to the permanent 
(direct)  field  due to  atoms  in  1-4 polarization  groups 
during an  induced dipole calculation, i.e.,  atoms that are 
in  polarization groups  separated  by two  groups from  the 
group containing the atom being polarized. The default value 
of 1.0 is used, if  the DIRECT-14-SCALE keyword is not given 
in either the parameter file or the keyfile.

DIVERGE  [real]      This  keyword  is used  by  the  SADDLE 
program to set the maximum allowed value of the ratio of the 
gradient length along the path to the total gradient norm at 
the  end of  a cycle  of minimization  perpendicular to  the 
path.  If  the value  provided  by  the DIVERGE  keyword  is 
exceeded, then another cycle  of maximization along the path 
is required. A default value of 0.005 is used in the absence 
of the DIVERGE keyword.

DPL-CUTOFF  [real]     Sets  the  cutoff  distance value  in 
Angstroms   for   bond  dipole-bond   dipole   electrostatic 
potential energy  interactions. The  energy for any  pair of 
bond dipole sites beyond the  cutoff distance will be set to 
zero.  Other keywords  can  be used  to  select a  smoothing 
scheme near the cutoff distance. The default cutoff distance 
in  the absence  of  the DPL-CUTOFF  keyword is  essentially 
infinite  for  nonperiodic  systems and  10.0  for  periodic 
systems.

DPL-TAPER [real]     This keyword allows modification of the 
cutoff  windows for  bond  dipole-bond dipole  electrostatic 
potential  energy interactions.  It is  similar in  form and 
action to the  TAPER keyword, except that  its value applies 
only to the vdw potential.  The default value in the absence 
of the  DPL-TAPER keyword is  to begin the cutoff  window at 
0.75 of the dipole cutoff distance.

ECHO [text  string]     The presence of  this keyword causes 
whatever text follows  it on the line to  be copied directly 
to the output file. This keyword is also active in parameter 
files. It has no default value;  if no text follows the ECHO 
keyword, a blank line is placed in the output file.

ELECTNEG [3 integers & 1 real]     This keyword provides the 
values for a single electronegativity bond length correction 
parameter.  The first  two integer  modifiers give  the atom 
class  numbers of  the  atoms  involved in  the  bond to  be 
corrected. The third  integer modifier is the  atom class of 
an  electronegative   atom.  In   the  case  of   a  primary 
correction, an  atom of  this third  class must  be directly 
bonded to an atom of the  second atom class. For a secondary 
correction, the third class is one atom removed from an atom 
of the second  class. The real number modifier  is the value 
in  Å by  which  the original  ideal bond  length  is to  be 
corrected.

EPSILONRULE   [GEOMETRIC/ARITHMETIC/HARMONIC/HHG]       This 
keyword  selects the  combining rule  used to  derive the  e 
value for  van der  Waals interactions.  The default  in the 
absence of the  EPSILONRULE keyword is to  use the GEOMETRIC 
mean of the individual e values of the two atoms involved in 
the van der Waals interaction.

EWALD     This keyword  turns on the use  of Ewald summation 
during computation of electrostatic interactions in periodic 
systems. In the current version  of TINKER, regular Ewald is 
used for polarizable atomic  multipoles, and smooth particle 
mesh  Ewald (PME)  is used  for charge-charge  interactions. 
Ewald summation is not  available for interactions involving 
bond-centered  dipoles. By  default, in  the absence  of the 
EWALD   keyword,  distance-based   cutoffs   are  used   for 
electrostatic interactions.

EWALD-ALPHA  [real]       Sets  the   value  of   the  Ewald 
coefficient  which  controls  the   width  of  the  Gaussian 
screening charges  during particle mesh Ewald  summation. In 
the absence  of the EWALD-ALPHA  keyword, a value  is chosen 
which causes  interactions outside the real-space  cutoff to 
be below  a fixed tolerance. For  most standard applications 
of Ewald summation, the program default should be used.

EWALD-BOUNDARY       This  keyword   invokes   the  use   of 
``vacuum''  boundary  conditions   during  Ewald  summation, 
corresponding to  the media surrounding the  system having a 
dielectric value  of 1.  The default in  the absence  of the 
EWALD-BOUNDARY  keyword  is   to  use  ``tinfoil''  boundary 
conditions where the surrounding media is assumed to have an 
infinite dielectric value.

EWALD-CUTOFF [real]      Sets the value in  Angstroms of the 
real-space distance  cutoff for use during  Ewald summation. 
By default,  in the absence  of the EWALD-CUTOFF  keyword, a 
value of 9.0 is used.

EWALD-FRACTION [real]     Sets the fraction between  0 and 1 
of  reciprocal space  included  in the  reciprocal sum  when 
using regular Ewald summation. The  keyword has no effect on 
PME  calculations. A  default value  of 0.5  is used  in the 
absence of the EWALD-FRACTION keyword.

EXIT-PAUSE     This keyword causes  TINKER programs to pause 
and wait  for a  carriage return at  the end  of executation 
prior to returning control to  the operating system. This is 
useful  to   keep  the   execution  window   open  following 
termination on  machines running Microsoft Windows  or Apple 
MacOS. The default in the absence of the EXIT-PAUSE keyword, 
is to return control to  the operating system immediately at 
program termination.

EXTRATERM [NONE/ONLY]      This keyword controls use  of the 
user defined extra potential energy  term. In the absence of 
a  modifying  option,  this  keyword turns  on  use  of  the 
potential. The NONE  option turns off use  of this potential 
energy term. The ONLY option  turns off all potential energy 
terms except for this one.

FCTMIN [real]     This keyword  sets a convergence criterion 
for successful  completion of a TINKER  optimization. If the 
value of the optimization  objective function, typically the 
potential energy, falls below the  value set by FCTMIN, then 
the optimization  is deemed  to have converged.  The default 
value  in the  absence of  the FCTMIN  keyword is  -1000000, 
effectively removing this criterion  as a possible agent for 
termination.

FORCEFIELD [name]      This keyword provides a  name for the 
force field to be used in the current calculation. Its value 
is usually set in the  master force field parameter file for 
the calculation  (see the PARAMETERS keyword)  instead of in 
the keyfile.

FRICTION  [real]      Sets  the   value  of  the  frictional 
coefficient in  ps-1 for  use with stochastic  dynamics. The 
default value used in the absence of the FRICTION keyword is 
91.0, which is generally appropriate for water.

GAMMA [real]     Sets the value of  the g angle of a crystal 
unit cell, i.e., the angle  between the a-axis and b-axis of 
a unit cell, or, equivalently,  the angle between the X-axis 
and  Z-axis of  a periodic  box.  The default  value in  the 
absence of the GAMMA keyword is  to set the g angle equal to 
the a angle as given by the keyword ALPHA.

GAMMA-HALGREN [real]      Sets the value of  the g parameter 
in Halgren's  buffered 14-7 vdw potential  energy functional 
form. In the absence of the DELTA-HALGREN keyword, a default 
value of 0.12 is used.

GAMMAMIN [real]     Sets the  convergence target value for g 
during searches  for maxima along the  quadratic synchronous 
transit used  by the SADDLE program.  The value of g  is the 
square of  the ratio  of the  gradient projection  along the 
path to  the total gradient.  A default value of  0.00001 is 
used in the absence of the GAMMAMIN keyword.
 
GAUSSTYPE [LJ-2/LJ-4/MM2-2/MM3-2/IN-PLACE]      This keyword 
specifies  the  underlying  vdw  form that  a  Gaussian  vdw 
approximation will attempt to fit.number of terms to be used 
in  a Gaussian  approximation of  the Lennard-Jones  van der 
Waals potential.  The text  modifier gives  the name  of the 
functional form  to be  used. Thus LJ-2  as a  modifier will 
result in a 2-Gaussian fit to a Lennard-Jones vdw potential. 
The GAUSSTYPE keyword only takes  effect when VDWTYPE is set 
to GAUSSIAN. This keyword has no default value.

GROUP [integer,  integer list]      This keyword  defines an 
atom group as a substructure within the full input molecular 
structure.  The value  of  the first  integer  is the  group 
number  which must be  in the  range from  1 to  the maximum 
number of  allowed groups. The remaining  intergers give the 
atom or  atoms contained in this  group as one or  more atom 
numbers or  ranges. Multiple  keyword lines  can be  used to 
specify additional  atoms in  the same  group. Note  that an 
atom can only be in one group, the last group to which it is 
assigned is the one used.

GROUP-INTER     This keyword  assigns a value of  1.0 to all 
inter-group interactions  and a value  of 0.0 to  all intra-
group interactions. For example, combination with the GROUP-
MOLECULE keyword provides for rigid-body calculations.

GROUP-INTRA     This keyword  assigns a value of  1.0 to all 
intra-group interactions  and a value  of 0.0 to  all inter-
group interactions.

GROUP-MOLECULE       This  keyword   sets  each   individual 
molecule in the system to be a separate atom group, but does 
not assign weights to group-group interactions.

GROUP-SELECT [2  integers, real]     This keyword  gives the 
weight in the  final potential energy of a  specified set of 
intra-  or intergroup  interactions.  The integer  modifiers 
give the  group numbers of  the groups involved. If  the two 
numbers are the same, then an intragroup set of interactions 
is specified.  The real modifier  gives the weight  by which 
all energetic  interactions in  this set will  be multiplied 
before  incorporation into  the final  potential energy.  If 
omitted as a keyword modifier, the weight will be set to 1.0 
by default.  If any SELECT-GROUP keywords  are present, then 
any  set of  interactions  not specified  in a  SELECT-GROUP 
keyword is given a zero  weight. The default when no SELECT-
GROUP  keywords  are  specified  is to  use  all  intergroup 
interactions with a weight of  1.0 and to set all intragroup 
interactions to zero.

HBOND [2 integers  & 2 reals]     This  keyword provides the 
values  for  the   MM3-style  directional  hydrogen  bonding 
parameters for a single pair of atoms. The integer modifiers 
give  the pair  of  atom class  numbers  for which  hydrogen 
bonding parameters  are to be  defined. The two  real number 
modifiers  give the  values  of the  minimum energy  contact 
distance in Å and the well  depth at the minimum distance in 
kcal/mole.     

HESS-CUTOFF [real]      This keyword  defines a  lower limit 
for significant Hessian  matrix elements. During computation 
of  the Hessian  matrix of  partial second  derivatives, any 
matrix elements  with absolute value below  HESS-CUTOFF will 
be set  to zero and  omitted from the sparse  matrix Hessian 
storage scheme  used by  TINKER. For most  calculations, the 
default in  the absence of  this keyword is zero,  i.e., all 
elements  will   be  stored.   For  most   Truncated  Newton 
optimizations the Hessian cutoff  will be chosen dynamically 
by the optimizer.

HGUESS  [real]     Sets  an  initial guess  for the  average 
value of the diagonal elements of the scaled inverse Hessian 
matrix  used by  the optimally  conditioned variable  metric 
optimization routine. A default value  of 0.4 is used in the 
absence of the HGUESS keyword.

IMPROPER [4  integers &  2 reals]     This  keyword provides 
the values for a single CHARMM-style improper dihedral angle 
parameter.

IMPROPTERM [NONE/ONLY]     This keyword  controls use of the 
CHARMM-style improper dihedral  angle potential energy term. 
In the absence of a  modifying option, this keyword turns on 
use of the potential. The NONE  option turns off use of this 
potential  energy  term.  The  ONLY  option  turns  off  all 
potential energy terms except for this one.

IMPROPUNIT  [real]      Sets  the  scale  factor  needed  to 
convert  the  energy  value  computed  by  the  CHARMM-style 
improper dihedral  angle potential into units  of kcal/mole. 
The  correct value  is force  field dependent  and typically 
provided in the  header of the master  force field parameter 
file. The  default value of  1.0 is used, if  the IMPROPUNIT 
keyword is  not given in  the force field parameter  file or 
the keyfile.

IMPTORS  [4 integers  & up  to 3  real/real/integer triples]     
This keyword  provides the  values for a  single AMBER-style 
improper torsional  angle parameter. The first  four integer 
modifiers give the atom class numbers for the atoms involved 
in  the   improper  torsional   angle  to  be   defined.  By 
convention, the third atom class of the four is the trigonal 
atom  on  which  the   improper  torsion  is  centered.  The 
torsional angle  computed is  literally that defined  by the 
four atom  classes in  the order  specified by  the keyword. 
Each of the remaining triples of real/real/integer modifiers 
give  the  half-amplitude,  phase   offset  in  degrees  and 
periodicity  of   a  particular  improper   torsional  term, 
respectively. Periodicities  through 3-fold are  allowed for 
improper torsional parameters.

IMPTORSTERM [NONE/ONLY]     This keyword controls use of the 
AMBER-style improper torsional  angle potential energy term. 
In the absence of a  modifying option, this keyword turns on 
use of the potential. The NONE  option turns off use of this 
potential  energy  term.  The  ONLY  option  turns  off  all 
potential energy terms except for this one.

IMPTORSUNIT  [real]      Sets  the scale  factor  needed  to 
convert  the  energy  value   computed  by  the  AMBER-style 
improper torsional angle potential  into units of kcal/mole. 
The  correct value  is force  field dependent  and typically 
provided in the  header of the master  force field parameter 
file. The default  value of 1.0 is used,  if the IMPTORSUNIT 
keyword is  not given in  the force field parameter  file or 
the keyfile.

INACTIVE [integer list]     Sets  the list of inactive atoms 
during  a TINKER  computation.  Individual potential  energy 
terms are not  computed when all atoms involved  in the term 
are  inactive. For  Cartesian  space calculations,  inactive 
atoms  are   not  allowed  to  move.   For  torsional  space 
calculations,  rotations  are  not allowed  when  there  are 
inactive atoms on  both sides of the  rotated bond. Multiple 
INACTIVE lines  can be present  in the keyfile, and  on each 
line the keyword can be followed by one or more atom numbers 
or ranges. If any INACTIVE keys are found, all atoms are set 
to active  except those  listed on  the INACTIVE  lines. The 
ACTIVE keyword overrides all  INACTIVE keywords found in the 
keyfile.

INTEGRATE  [VERLET/BEEMAN/STOCHASTIC/RIGIDBODY]      Chooses 
the   integration  method   for   propagation  of   dynamics 
trajectories. The  keyword is followed  on the same  line by 
the name  of the  option. Standard Newtonian  MD can  be run 
using  either  VERLET for  the  Velocity  Verlet method,  or 
BEEMAN  for the  velocity  form of  Bernie Brook's  ``Better 
Beeman'' method. A Velocity Verlet-based stochastic dynamics 
trajectory is selected by  the STOCHASTIC modifier. A rigid-
body dynamics method is  selected by the RIGIDBODY modifier. 
The  default  integration  scheme  is MD  using  the  BEEMAN 
method. Note the RIGIDBODY option is still under development 
and should  be treated as  experimental code in  the current 
version of TINKER.

INTMAX   [integer]       Sets    the   maximum   number   of 
interpolation cycles  that will  be allowed during  the line 
search phase  of an optimization. All  gradient-based TINKER 
optimization  routines  use  a common  line  search  routine 
involving quadratic  extrapolation and  cubic interpolation. 
If the  value of INTMAX is  reached, an error status  is set 
for the line  search and the search is repeated  with a much 
smaller initial step size. The  default value in the absence 
of this  keyword is  optimization routine dependent,  but is 
usually in the range 5 to 10.

LAMBDA [real]     This keyword sets  the value of the l path 
parameter  for free  energy  perturbation calculations.  The 
real  number  modifier  specifies  the  position  along  the 
mutation  path and  must be  a number  in the  range from  0 
(initial  state)  to  1  (final  state).  The  actual  atoms 
involved in the mutation  are given separately in individual 
MUTATE keyword lines.

LBFGS-VECTORS  [integer]     Sets  the number  of correction 
vectors  used  by  the  limited-memory  L-BFGS  optimization 
routine.  The  current  maximum  allowable  value,  and  the 
default in the absence of the LBFGS-VECTORS keyword is 15.

LIGHTS     This  keyword turns on Method  of Lights neighbor 
generation for  the charge-charge  potential and any  of the 
van der  Waals potentials. This method  will yield identical 
energetic results to the standard double loop method. Method 
of Lights  will be faster when  the volume of a  sphere with 
radius equal to the nonbond cutoff distance is significantly 
less than  half the  volume of the  total system  (i.e., the 
full molecular system, the crystal unit cell or the periodic 
box).

MAXITER   [integer]       Sets   the   maximum   number   of 
minimization iterations that will  be allowed for any TINKER 
program  that   uses  any  of  the   nonlinear  optimization 
routines. The default  value in the absence  of this keyword 
is  program dependent,  but is  always set  to a  very large 
number.

METAL      This keyword  provides  the values  for a  single 
transition metal  ligand field parameter. Note  this keyword 
is  present in  the  code,  but not  active  in the  current 
version of TINKER.

METALTERM [NONE/ONLY]      This keyword controls use  of the 
transition metal ligand field  potential energy term. In the 
absence of a modifying option,  this keyword turns on use of 
the  potential.  The  NONE  option turns  off  use  of  this 
potential  energy  term.  The  ONLY  option  turns  off  all 
potential  energy  terms  except  for this  one.  Note  this 
keyword  is present  in  the  code, but  not  active in  the 
current version of TINKER.

MM2-STRBND      This keyword  switches the  behavior of  the 
stretch-bend  potential function  to  match the  formulation 
used by the MM2 force field.  In MM2, stretching of bonds to 
attached hydrogen  atoms is  not including in  computing the 
stretch-bend cross term energy.  The default behavior in the 
absence of this keyword is to include stretching of attached 
hydrogen atoms as in the MM3 force field.

MPOLE-12-SCALE   [real]       This    keyword   provides   a 
multiplicative  scale factor  that is  applied to  permanent 
atomic  multipole  electrostatic  interactions  between  1-2 
connected atoms,  i.e., atoms that are  directly bonded. The 
default value of 0.0 is  used, if the MPOLE-12-SCALE keyword 
is not given in either the parameter file or the keyfile.

MPOLE-13-SCALE   [real]       This    keyword   provides   a 
multiplicative  scale factor  that is  applied to  permanent 
atomic  multipole   electrostatic interactions  between  1-3 
connected  atoms,  i.e.,  atoms separated  by  two  covalent 
bonds. The  default value of  0.0 is used, if  the MPOLE-13-
SCALE keyword is  not given in either the  parameter file or 
the keyfile.

MPOLE-14-SCALE   [real]       This    keyword   provides   a 
multiplicative  scale factor  that is  applied to  permanent 
atomic  multipole   electrostatic interactions  between  1-4 
connected  atoms, i.e.,  atoms separated  by three  covalent 
bonds. The  default value of  1.0 is used, if  the MPOLE-14-
SCALE keyword is  not given in either the  parameter file or 
the keyfile.

MPOLE-15-SCALE   [real]       This    keyword   provides   a 
multiplicative  scale factor  that is  applied to  permanent 
atomic  multipole   electrostatic interactions  between  1-5 
connected  atoms, i.e.,  atoms  separated  by four  covalent 
bonds. The  default value of  1.0 is used, if  the MPOLE-15-
SCALE keyword is  not given in either the  parameter file or 
the keyfile.

MPOLE-CUTOFF [real]      Sets the  cutoff distance  value in 
Angstroms    for   atomic    multipole   potential    energy 
interactions. The  energy for any  pair of sites  beyond the 
cutoff distance will  be set to zero. Other  keywords can be 
used to select a smoothing  scheme near the cutoff distance. 
The default  cutoff distance  in the  absence of  the MPOLE-
CUTOFF keyword  is infinite for nonperiodic  systems and 9.0 
for periodic systems.

MPOLE-TAPER [real]      This keyword allows  modification of 
the  cutoff window  for  atomic  multipole potential  energy 
interactions. It is similar in  form and action to the TAPER 
keyword, except  that its value  applies only to  the atomic 
multipole potential. The default value in the absence of the 
MPOLE-TAPER keyword is to begin the cutoff window at 0.65 of 
the corresponding cutoff distance.

MPOLETERM [NONE/ONLY]      This keyword controls use  of the 
atomic  multipole electrostatics  potential energy  term. In 
the absence of a modifying option, this keyword turns on use 
of  the potential.  The NONE  option turns  off use  of this 
potential  energy  term.  The  ONLY  option  turns  off  all 
potential energy terms except for this one.

MULTIPOLE [5  lines with: 3  integers &  1 real; 3  reals; 1 
real; 2 reals; 3 reals]     This keyword provides the values 
for a set of atomic multipole parameters at a single site. A 
complete keyword entry consists  of three consequtive lines, 
the first line containing the  MULTIPOLE keyword and the two 
following  lines. The  first  line  contains three  integers 
which  define the  atom  type on  which  the multipoles  are 
centered, and the Z-axis and  X-axis defining atom types for 
this center.  The real  number on the  first line  gives the 
monopole  (atomic  charge)  in electrons.  The  second  line 
contains three  real numbers  which give the  X-, Y-  and Z-
components  of the  atomic dipole  in electron-Å.  The final 
three lines, consisting  of one, two and  three real numbers 
give the  upper triangle of the  traceless atomic quadrupole 
tensor in electron-Å2.

MUTATE  [3 integers]      This  keyword is  used to  specify 
atoms  to   be  mutated  during  free   energy  perturbation 
calculations.  The first  integer  modifier  gives the  atom 
number  of an  atom in  the  current system.  The final  two 
modifier values  give the  atom types corresponding  the the 
l=0 and l=1 states of the specified atom.

MUTUAL-11-SCALE   [real]       This   keyword   provides   a 
multiplicative scale  factor that is applied  to the induced 
(mutual)  field due  to  atoms within  a polarization  group 
during an  induced dipole calculation, i.e.,  atoms that are 
in the same polarization group  as the atom being polarized. 
The default  value of  1.0 is  used, if  the MUTUAL-11-SCALE 
keyword is  not given  in either the  parameter file  or the 
keyfile.

MUTUAL-12-SCALE   [real]       This   keyword   provides   a 
multiplicative scale  factor that is applied  to the induced 
(mutual)  field  due to  atoms  in  1-2 polarization  groups 
during an  induced dipole calculation, i.e.,  atoms that are 
in  polarization  groups  directly connected  to  the  group 
containing the  atom being  polarized. The default  value of 
1.0 is used, if the  MUTUAL-12-SCALE keyword is not given in 
either the parameter file or the keyfile.

MUTUAL-13-SCALE   [real]       This   keyword   provides   a 
multiplicative scale  factor that is applied  to the induced 
(mutual)  field  due to  atoms  in  1-3 polarization  groups 
during an  induced dipole calculation, i.e.,  atoms that are 
in polarization groups separated by one group from the group 
containing the  atom being  polarized. The default  value of 
1.0 is used, if the  MUTUAL-13-SCALE keyword is not given in 
either the parameter file or the keyfile.

MUTUAL-14-SCALE   [real]       This   keyword   provides   a 
multiplicative scale  factor that is applied  to the induced 
(mutual)  field  due to  atoms  in  1-4 polarization  groups 
during an  induced dipole calculation, i.e.,  atoms that are 
in  polarization groups  separated  by two  groups from  the 
group containing the atom being polarized. The default value 
of 1.0 is used, if  the MUTUAL-14-SCALE keyword is not given 
in either the parameter file or the keyfile.

NEIGHBOR-GROUPS     This keyword causes the attached atom to 
be used  in determining the charge-charge  neighbor distance 
for all  monovalent atoms in  the molecular system.  Its use 
causes all monovalent atoms to  be treated the same as their 
attached atoms for purposes of including or scaling 1-2, 1-3 
and 1-4 interactions. This option  works only for the simple 
charge-charge  electrostatic potential;  it does  not affect 
bond dipole  or atomic  multipole potentials.  The NEIGHBOR-
GROUPS scheme is  similar to that used by  some common force 
fields such as ENCAD.

NEUTRAL-GROUPS     The  keyword causes the attached  atom to 
be used in determining  the charge-charge interaction cutoff 
distance for  all monovalent atoms in  the molecular system. 
Its use reduces cutoff discontinuities by avoiding splitting 
many  of the  largest  charge separations  found in  typical 
molecules.  Note  that  this  keyword  does  not  rigorously 
implement the usual  concept of a ``neutral  group'' as used 
in the  literature with  AMBER/OPLS and other  force fields. 
This  option   works  only  for  the   simple  charge-charge 
electrostatic potential;  it does not affect  bond dipole or 
atomic multipole potentials.

NEWHESS  [integer]       Sets  the  number   of  algorithmic 
iterations between  recomputation of the Hessian  matrix. At 
present  this keyword  applies exclusively  to optimizations 
using the Truncated Newton method.  The default value in the 
absence of this keyword is  1, i.e., the Hessian is computed 
on every iteration.

NEXTITER [integer]     Sets the  iteration number to be used 
for  the  first iteration  of  the  current computation.  At 
present  this  keyword  applies to  optimization  procedures 
where  its use  can effect  convergence criteria,  timing of 
restarts, and so  forth. The default in the  absence of this 
keyword is to take the initial iteration as iteration 1.

NOVERSION     Turns off the  use of version numbers appended 
to  the  end  of  filenames as  the  method  for  generating 
filenames  for  updated  copies  of an  existing  file.  The 
presence of this keyword results in direct use of input file 
names without  a search  for the highest  available version, 
and requires the entry of specific output file names in many 
additional  cases.  By  default,  in  the  absence  of  this 
keyword, TINKER generates and  attaches version numbers in a 
manner similar to the  Digital OpenVMS operating system. For 
example, subsequent  new versions  of the  file molecule.xyz 
would be written  first to the file  molecule.xyz_2, then to 
molecule.xyz_3, etc.

OCTAHEDRON      Specifies that  the  periodic  ``box'' is  a 
truncated  octahedron  with   maximal  distance  across  the 
truncated  octahedron as  given by  the A-AXIS  keyword. All 
other unit cell and  periodic box size-defining keywords are 
ignored if the OCTAHEDRON keyword is present.

OPBEND [2 integers  & 1 real]     This  keyword provides the 
values  for a  single Allinger  MM-style out-of-plane  angle 
bending potential  parameter. The first integer  modifier is 
the atom class  of the central trigonal atom  and the second 
integer is the atom class of the out-of-plane atom. The real 
number modifier gives the force  constant value for the out-
of-plane angle. The default units for the force constant are 
kcal/mole/radian2,  but  this  can  be  controlled  via  the 
OPBENDUNIT keyword.

OPBENDTERM [NONE/ONLY]     This keyword  controls use of the 
Allinger  MM-style  out-of-plane  bending  potential  energy 
term. In  the absence  of a  modifying option,  this keyword 
turns on use of the potential. The NONE option turns off use 
of this potential energy term. The ONLY option turns off all 
potential energy terms except for this one.

OPBENDUNIT  [real]      Sets  the  scale  factor  needed  to 
convert the  energy value computed by  the Allinger MM-style 
out-of-plane bending potential into  units of kcal/mole. The 
correct  value  is  force   field  dependent  and  typically 
provided in the  header of the master  force field parameter 
file. The  default of (p/180)2  = 0.0003046 is used,  if the 
OPBENDUNIT keyword is not given in the force field parameter 
file or the keyfile.

OPDIST [4 integers  & 1 real]     This  keyword provides the 
values   for  a   single  out-of-plane   distance  potential 
parameter. The first  integer modifier is the  atom class of 
the central  trigonal atom  and the three  following integer 
modifiers are the atom classes  of the three attached atoms. 
The  real number  modifier  is the  force  constant for  the 
harmonic  function  of  the  out-of-plane  distance  of  the 
central atom. The  default units for the  force constant are 
kcal/mole/Å2, but this can  be controlled via the OPDISTUNIT 
keyword.

OPDISTTERM [NONE/ONLY]     This keyword  controls use of the 
out-of-plane distance potential energy  term. In the absence 
of  a modifying  option, this  keyword turns  on use  of the 
potential. The NONE  option turns off use  of this potential 
energy term. The ONLY option  turns off all potential energy 
terms except for this one.

OPDISTUNIT  [real]      Sets  the  scale  factor  needed  to 
convert  the  energy  value  computed  by  the  out-of-plane 
distance  potential into  units  of  kcal/mole. The  correct 
value is force field dependent and typically provided in the 
header of the master force field parameter file. The default 
value of 1.0 is used, if the OPDISTUNIT keyword is not given 
in the force field parameter file or the keyfile.

OVERWRITE     Causes TINKER programs, such as minimizations, 
that output intermediate coordinate  sets to create a single 
disk file for the intermediate results which is successively 
overwritten with  the new  intermediate coordinates  as they 
become available.  This keyword is essentially  the opposite 
of the SAVECYCLE keyword.

PARAMETERS [file  name]     Provides  the name of  the force 
field  parameter file  to  be used  for  the current  TINKER 
calculation. The standard file  name extension for parameter 
files, .prm, is an optional  part of the file name modifier. 
The default in  the absence of the PARAMETERS  keyword is to 
look for  a parameter file  with the  same base name  as the 
molecular  system and  ending in  the .prm  extension. If  a 
valid parameter  file is not  found, the user will  asked to 
provide a file name interactively.

PIATOM [1 integer  & 3 reals]     This  keyword provides the 
values for the pisystem MO potential parameters for a single 
atom class belonging to a pisystem.

PIBOND [2 integers & 2  reals]     This keyword provides the 
values for the pisystem MO potential parameters for a single 
type of pisystem bond.

PISYSTEM  [integer list]      This  keyword  sets the  atoms 
within a  molecule that are  part of a  conjugated p-system. 
The keyword is  followed on the same line by  a list of atom 
numbers and/or atom ranges that constitute the p-system. The 
Allinger MM force  fields use this information to  set up an 
MO  calculation used  to scale  bond and  torsion parameters 
involving p-system atoms.

PME-GRID [3  integers]     This keyword sets  the dimensions 
of  the   charge  grid  used  during   particle  mesh  Ewald 
summation. The three  modifiers give the size  along the X-, 
Y-  and Z-axes,  respectively. If  either the  Y- or  Z-axis 
dimensions are  omitted, then they  are set equal to  the X-
axis dimension. The  default in the absence  of the PME-GRID 
keyword  is to  set the  grid size  along each  axis to  the 
smallest power of  2, 3 and/or 5 which is  at least as large 
as 1.5 times the axis length  in Angstoms. Note that the FFT 
used by PME is not restricted to, but is most efficient for, 
grid sizes which are powers of 2, 3 and/or 5.

PME-ORDER [integer]      This keyword sets the  order of the 
B-spline  interpolation  used  during  particle  mesh  Ewald 
summation. A  default value of 8  is used in the  absence of 
the PME-ORDER keyword.

POLAR-11-SCALE   [real]       This    keyword   provides   a 
multiplicative scale factor that  is applied to polarization 
interactions  within a  polarization group,  i.e., pairs  of 
atoms that are  in the same polarization  group. The default 
value of 0.0  is used, if the POLAR-11-SCALE  keyword is not 
given in either the parameter file or the keyfile.

POLAR-12-SCALE   [real]       This    keyword   provides   a 
multiplicative scale factor that  is applied to polarization 
interactions between 1-2 polarization groups, i.e., pairs of 
atoms that  are in  directly connected  polarization groups. 
The  default value  of 0.0  is used,  if the  POLAR-12-SCALE 
keyword is  not given  in either the  parameter file  or the 
keyfile.

POLAR-13-SCALE   [real]       This    keyword   provides   a 
multiplicative scale factor that  is applied to polarization 
interactions between 1-3 polarization groups, i.e., pairs of 
atoms that are in polarization groups separated by one other 
group. The  default value of  0.0 is used, if  the POLAR-13-
SCALE keyword is  not given in either the  parameter file or 
the keyfile.

POLAR-14-SCALE   [real]       This    keyword   provides   a 
multiplicative scale factor that  is applied to polarization 
interactions between 1-4 polarization groups, i.e., pairs of 
atoms that are in polarization groups separated by two other 
groups. The default  value of 1.0 is used,  if the POLAR-14-
SCALE keyword is  not given in either the  parameter file or 
the keyfile.

POLAR-DAMP  [2  reals]      Controls  the  strength  of  the 
damping  function  applied  to induced  dipoles  and  dipole 
polarization interaction  energies. The first  modifier sets 
the  radius in  Angstoms of  a hypothetical  atom with  unit 
polarizability,  while the  second modifier  sets the  scale 
factor  for  the  exponent  of the   damping  function.  The 
default values for the radius and the scale factor are 1.662 
and  1.0, respectively.  Damping is  eliminated entirely  by 
using this keyword to set the radius value to zero. 

POLAR-EPS  [real]      This  keyword  sets  the  convergence 
criterion  applied  during  computation  of  self-consistent 
induced dipoles. The calculation is deemed to have converged 
when the  rms change (in  Debyes) of the induced  dipoles at 
all polarizable sites is less  than the value specified with 
this  keyword.  The default  value  in  the absence  of  the 
keyword is 10-6 Debyes.

POLAR-OLD     This keyword  selects the polarization damping 
scheme used  in TINKER 3.8  and earlier. Beginning  with the 
3.9 release,  TINKER implements  a short  range polarization 
damping  method  due  to  Thole.  This  option  is  included 
primarily  to  allow  continued  use  of  the  early  TINKER 
polarizable water model based  on the originally implemented 
flat multiplicative damping.

POLAR-SOR [real]     Sets  a successive overrelaxation (SOR) 
factor  for use  in computation  of induced  atomic dipoles. 
Optimal  values  for this  keyword  will  speed the  induced 
dipole   calculation,  and   poor  values   can  result   in 
convergence failure. The default value in the absence of the 
POLAR-SOR keyword is 0.7 which often a reasonable value when 
short-range  intramolecular  polarization  is  present.  For 
models lacking  intramolecular polarization,  keyword values 
closer to 1.0 may be optimal.

POLARIZATION [DIRECT/MUTUAL]     Selects  between the use of 
direct and mutual dipole  polarization for force fields that 
incorporate  the  polarization  term.  The  DIRECT  modifier 
avoids an iterative calculation  by using only the permanent 
electric field in computation of induced dipoles. The MUTUAL 
option,  which  is  the  default   in  the  absence  of  the 
POLARIZATION keyword, iterates the  induced dipoles to self-
consistency.

POLARIZE [1  integer, 1  real & up  to 4  integers]     This 
keyword  provides  the values  for  a  single atomic  dipole 
polarizability parameter. The integer modifier, if positive, 
gives  the  atom  type  number for  which  a  polarizability 
parameter is to be defined. If the first integer modifier is 
negative, then the parameter value to follow applies only to 
the individual atom whose atom number is the negative of the 
modifier. The  real number modifier  gives the value  of the 
dipole  polarizability in  Å3. The  final integer  modifiers 
list the atom  type numbers of atoms directly  bonded to the 
current atom and which will be  considered to be part of the 
current atom's polarization group.

POLARIZETERM  [NONE/ONLY]     This  keyword controls  use of 
the atomic dipole polarization potential energy term. In the 
absence of a modifying option,  this keyword turns on use of 
the  potential.  The  NONE  option turns  off  use  of  this 
potential  energy  term.  The  ONLY  option  turns  off  all 
potential energy terms except for this one.

POLYMER-CUTOFF [real]      Sets the  value of  an additional 
cutoff parameter  needed for infinite polymer  systems. This 
value must be set to less than half the minimal periodic box 
dimension and  should be  greater than the  largest possible 
interatomic  distance  that can  be  subject  to scaling  or 
exclusion  as  a  local   electrostatic  or  van  der  Waals 
interaction.  The default  in  the absence  of the  POLYMER-
CUTOFF keyword is 5.5 Angstroms.

PRINTOUT  [integer]     A  general  parameter for  iterative 
procedures  such as  minimizations that  sets the  number of 
iterations  between  writes  of status  information  to  the 
standard output.  The default  value in  the absence  of the 
keyword is  1, i.e., the  calculation status is  given every 
iteration.

RADIUSRULE  [ARITHMETIC/GEOMETRIC/CUBIC-MEAN]      Sets  the 
functional   form  of   the   radius   combining  rule   for 
heteroatomic  van der  Waals potential  energy interactions. 
The default in  the absence of the RADIUSRULE  keyword is to 
use  the arithmetic  mean combining  rule to  get radii  for 
heteroatomic interactions.

RADIUSSIZE [RADIUS/DIAMETER]     Determines whether the atom 
size values given in van  der Waals parameters read from VDW 
keyword  statements  are  interpreted as  atomic  radius  or 
diameter  values.   The  default  in  the   absence  of  the 
RADIUSSIZE keyword is to assume that vdw size parameters are 
given as radius values.

RADIUSTYPE  [R-MIN/SIGMA]     Determines  whether atom  size 
values  given in  van  der Waals  parameters  read from  VDW 
keyword  statements  are  interpreted as  potential  minimum 
(Rmin)  or LJ-style  sigma (s)  values. The  default in  the 
absence of the RADIUSTYPE keyword is to assume that vdw size 
parameters are given as Rmin values.

RANDOMSEED [integer]     Followed by  an integer value, this 
keyword sets  the initial seed  value for the  random number 
generator  used by  TINKER. Setting  RANDOMSEED to  the same 
value as an earlier run will allow exact reproduction of the 
earlier calculation.  (Note that  this will not  hold across 
different  machine types.)  RANDOMSEED  should be  set to  a 
positive integer less  than about 2 billion.  In the absence 
of the  RANDOMSEED keyword  the seed is  chosen ``randomly'' 
based upon  the number of  seconds that have elapsed  in the 
current decade.

RATTLE  [BONDS/ANGLES/DIATOMIC/TRIATOMIC/WATER]      Invokes 
the  rattle  algorithm,  a  velocity version  of  shake,  on 
portions of  a molecular  system during a  molecular dynamic 
calculation. The  RATTLE keyword can  be followed by  any of 
the modifiers  shown, in which  case all occurrences  of the 
modifier species are constrained  at ideal values taken from 
the bond and angle parameters of  the force field in use. In 
the absence of any modifier,  RATTLE constrains all bonds to 
hydrogen atoms at ideal bond lengths.
  
RATTLE-BOND [2 integers]     This  keyword allows the use of 
rattle (see above) on a the bond between the two atoms whose 
numbers are specified on the  keyword line. If the two atoms 
are  involved in  a covalent  bond, then  their distance  is 
constrained to the  ideal bond length from  the force field. 
For  nonbonded  atoms,  the rattle  constraint  fixes  their 
distance at the distance in the input coordinate file.
  
REACTIONFIELD  [2  reals  &   1  integer]      This  keyword 
provides parameters needed for  the reaction field potential 
energy calculation.  The two real modifiers  give the radius 
of  the  dielectric  cavity  and   the  ratio  of  the  bulk 
dielectric outside the cavity to that inside the cavity. The 
integer modifier gives  the number of terms  in the reaction 
field  summation  to   be  used.  In  the   absence  of  the 
REACTIONFIELD keyword,  the default  values are a  cavity of 
radius 1000000 Å,  a dielectric ratio of 80 and  use of only 
the first term of the reaction field summation.

REDUCE [real]      Specifies the  fraction between  zero and 
one   by  which   the  path   between  starting   and  final 
conformational state  will be shortened at  each major cycle 
of the  transition state  location algorithm  implemented by 
the SADDLE program.  This causes the path  endpoints to move 
up and out of the  terminal structures toward the transition 
state region.  In favorable  cases, a  nonzero value  of the 
REDUCE  modifier can  speed  convergence  to the  transition 
state.  The  default value  in  the  absence of  the  REDUCE 
keyword is zero.

RESTRAIN-ANGLE  [3  integers  & 3  reals]      This  keyword 
implements a flat-welled harmonic potential that can be used 
to restrain  the angle between  three atoms to lie  within a 
specified  angle   range.  The  initial   integer  modifiers 
contains the atom numbers of  the three atoms whose angle is 
to be restrained.  The first two real  number modifiers give 
the lower and  upper bounds in degrees on  the allowed angle 
values.  If  the angle  lies  between  the lower  and  upper 
bounds, the restraint potential is zero. Outside the bounds, 
a  harmonic potential  with force  constant in  kcal/degree2 
given by  the final real  modifier is applied. If  the force 
constant is omitted, a default value of 10.0 is used. If all 
the  real   modifiers  are  omitted,  then   the  atoms  are 
restrained  to  an angle  of  zero  with the  default  force 
constant.

RESTRAIN-DISTANCE [2  integers &  3 reals]      This keyword 
implements a flat-welled harmonic potential that can be used 
to restrain  two atoms  to lie  within a  specified distance 
range.  The  initial  integer modifiers  contains  the  atom 
numbers of  the two  atoms to be  restrained. The  first two 
real number  modifiers give  the lower  and upper  bounds in 
Angstroms on the allowed distance values. If the interatomic 
distance  lies  between  the  lower and  upper  bounds,  the 
restraint potential is zero.  Outside the bounds, a harmonic 
potential with force constant in  kcal/Å2 given by the final 
real modifier is applied. If  the force constant is omitted, 
a default value of 100.0 is  used. If all the real modifiers 
are omitted, then the atoms are restrained to an interatomic 
distance of zero with the default force constant.

RESTRAIN-POSITION  [1 integer  & 4  reals]     This  keyword 
provides the  ability to  restrain an  individual atom  to a 
specified coordinate position.  The initial integer modifier 
contains the atom  number of the atom to  be restrained. The 
first three  real number  modifiers give the  X-, Y-  and Z-
coordinates to  which the atom  is tethered. The  final real 
modifier sets the force constant in kcal/Å2 for the harmonic 
restraint  potential. If  the force  constant is  omitted, a 
default value  of 100.0 is  used. If all the  real modifiers 
are omitted, then the atom  is restrained to the origin with 
the default force constant.

RESTRAIN-TORSION  [4 integers  & 3  reals]     This  keyword 
implements a flat-welled harmonic potential that can be used 
to restrain  the torsional angle  between four atoms  to lie 
within  a   specified  angle  range.  The   initial  integer 
modifiers contains the atom numbers  of the four atoms whose 
torsional angle, computed in the atom order listed, is to be 
restrained.  The first  two real  number modifiers  give the 
lower and upper  bounds in degrees on  the allowed torsional 
angle values. The angle values  given can wrap around across 
-180 and  +180 degrees. Outside  the allowed angle  range, a 
harmonic potential with force constant in kcal/degree2 given 
by the final real modifier is applied. If the force constant 
is omitted, a default value of  1.0 is used. If all the real 
modifiers are  omitted, then the  atoms are restrained  to a 
torsional angle of zero with the default force constant.

RESTRAINTERM  [NONE/ONLY]     This  keyword controls  use of 
the restraint  potential energy terms.  In the absence  of a 
modifying  option,  this  keyword  turns  on  use  of  these 
potentials. The NONE option turns off use of these potential 
energy terms. The ONLY option turns off all potential energy 
terms except for these terms.
 
RXNFIELDTERM  [NONE/ONLY]     This  keyword controls  use of 
the  reaction  field  continuum solvation  potential  energy 
term. In  the absence  of a  modifying option,  this keyword 
turns on use of the potential. The NONE option turns off use 
of this potential energy term. The ONLY option turns off all 
potential energy terms except for this one.

SADDLEPOINT     The presence of  this keyword allows Newton-
style second  derivative-based optimization routine  used by 
NEWTON,   NEWTROT  and   other  programs   to  converge   to 
saddlepoints as well as minima  on the potential surface. By 
default, in  the absence of the  SADDLEPOINT keyword, checks 
are applied  that prevent  convergence to  stationary points 
having directions of negative curvature.

SAVE-CYCLE     This keyword causes  TINKER programs, such as 
minimizations, that  output intermediate coordinate  sets to 
save each successive set  to the next consecutively numbered 
cycle file.  The SAVE-CYCLE keyword  is the opposite  of the 
OVERWRITE keyword.

SAVE-INDUCED      This   keyword  causes   TINKER  molecular 
dynamics  calculations   that  involve   polarizable  atomic 
multipoles  to  save  the   values  of  the  induced  dipole 
components  on each  polarizable  atom to  a separate  cycle 
file. These files are written whenever the atomic coordinate 
snapshots are written during  the dynamics run. Each induced 
dipole  file name  contains  as a  suffix  the cycle  number 
followed by the letter u. 

SAVE-VELOCITY      This  keyword   causes  TINKER  molecular 
dynamics  calculations to  save the  values of  the velocity 
components  on each  atom to  a separate  cycle file.  These 
files are  written whenever the atomic  coordinate snapshots 
are written during the dynamics run. Each velocity file name 
contains as a suffix the cycle number followed by the letter 
v.

SOLVATE [ASP/SASA/ONION/STILL/HCT/ACE/GBSA]      Use of this 
keyword during energy calculations  with any of the standard 
force  fields turns  on  a continuum  solvation free  energy 
term. Several algorithms are available based on the modifier 
used: ASP= Eisenberg-McLachlan ASP  method using the Wesson-
Eisenberg vacuum-to-water parameters; SASA= the Ooi-Scheraga 
SASA method; ONION= the  original 1990 Still ``Onion-shell'' 
GB/SA method;  STILL= the 1997 analytical  GB/SA method from 
Still's  group;  HCT=  the pairwise  descreening  method  of 
Hawkins, Cramer  and Truhlar; ACE= the  analytical continuum 
solvation method from the Karplus group; GBSA= equivalent to 
the STILL modifier. At present, GB/SA-style methods are only 
valid  for  force  fields  that use  simple  partial  charge 
electrostatics. The ACE method is not recommended for use in 
the  current  version  of  TINKER; the  algorithm  is  fully 
implemented in  the source code,  but is not  yet completely 
parametrized.

SOLVATETERM [NONE/ONLY]     This keyword controls use of the 
macroscopic solvation potential energy  term. In the absence 
of  a modifying  option, this  keyword turns  on use  of the 
potential. The NONE  option turns off use  of this potential 
energy term. The ONLY option  turns off all potential energy 
terms except for this one.

SPACEGROUP [name]      This keyword selects the  space group 
to  be  used  in  manipulation of  crystal  unit  cells  and 
asymmetric units. The name option must be chosen from one of 
the following currently implemented space groups: P1, P1(-), 
P21, Cc,  P21/a, P21/n, P21/c, C2/c,  P212121, Pna21, Pn21a, 
Cmc21, Pccn, Pbcn, Pbca, P41, I41/a, P4(-)21c, P4(-)m2, R3c, 
P6(3)/mcm, Fm3(-)m, Im3(-)m.

SPHERE [4  reals, or  1 integer &  1 real]      This keyword 
provides an alternative to  the ACTIVE and INACTIVE keywords 
for specification of  subsets of active atoms.  If four real 
number modifiers are provided, the  first three are taken as 
X-, Y- and  Z-coordinates and the fourth is the  radius of a 
sphere  centered at  these  coordinates. In  this case,  all 
atoms within the sphere at  the start of the calculation are 
active throughout the calculation, while all other atoms are 
inactive.  Similarly  if one  integer  and  real number  are 
given, an ``active''  sphere with radius set by  the real is 
centered on  the system atom  with atom number given  by the 
integer  modifier.  Multiple  SPHERE keyword  lines  can  be 
present in  a single keyfile,  and the list of  active atoms 
specified by the spheres is cumulative.

STEPMAX [real]     This keyword  and its modifying value set 
the  maximum size  of  an individual  step  during the  line 
search  phase  of  conjugate  gradient  or  truncated  Newon 
optimizations. The step size is  computed as the norm of the 
vector of changes in parameters being optimized. The default 
value  depends  on the  particular  TINKER  program, but  is 
usually in the range from 1.0  to 5.0 when not specified via 
the STEPMAX keyword.

STEPMIN [real]     This keyword  and its modifying value set 
the  minimum size  of  an individual  step  during the  line 
search  phase  of  conjugate  gradient  or  truncated  Newon 
optimizations. The step size is  computed as the norm of the 
vector of changes in parameters being optimized. The default 
value is usually  set to about 10-16 when  not specified via 
the STEPMIN keyword.

STRBND [1 integer  & 3 reals]     This  keyword provides the 
values  for  a  single  stretch-bend  cross  term  potential 
parameter. The integer modifier  gives the atom class number 
for the central atom of  the bond angle involved in stretch-
bend interactions. The real  number modifiers give the force 
constant  values to  be used  when the  central atom  of the 
angle is  attached to 0,  1 or 2 additional  hydrogen atoms, 
respectively. The  default units for the  stretch-bend force 
constant are kcal/mole/Å-degree, but  this can be controlled 
via the STRBNDUNIT keyword.

STRBNDTERM [NONE/ONLY]     This keyword  controls use of the 
bond stretching-angle  bending cross term  potential energy. 
In the absence of a  modifying option, this keyword turns on 
use of the potential. The NONE  option turns off use of this 
potential  energy  term.  The  ONLY  option  turns  off  all 
potential energy terms except for this one.

STRBNDUNIT  [real]      Sets  the  scale  factor  needed  to 
convert the  energy value  computed by the  bond stretching-
angle bending cross term  potential into units of kcal/mole. 
The  correct value  is force  field dependent  and typically 
provided in the  header of the master  force field parameter 
file. The  default value of  1.0 is used, if  the STRBNDUNIT 
keyword is  not given in  the force field parameter  file or 
the keyfile.

STRTORS [2 integers & 1  real]     This keyword provides the 
values  for a  single stretch-torsion  cross term  potential 
parameter.  The two  integer modifiers  give the  atom class 
numbers for  the atoms involved  in the central bond  of the 
torsional  angles to  be  parameterized.  The real  modifier 
gives the  value of  the stretch-torsion force  constant for 
all  torsional angles  with  the defined  central bond  atom 
classes.  The default  units for  the stretch-torsion  force 
constant can be controlled via the STRTORUNIT keyword.

STRTORTERM [NONE/ONLY]     This keyword  controls use of the 
bond stretching-torsional angle cross term potential energy. 
In the absence of a  modifying option, this keyword turns on 
use of the potential. The NONE  option turns off use of this 
potential  energy  term.  The  ONLY  option  turns  off  all 
potential energy terms except for this one.

STRTORUNIT  [real]      Sets  the  scale  factor  needed  to 
convert the  energy value  computed by the  bond stretching-
torsional  angle   cross  term   potential  into   units  of 
kcal/mole. The  correct value  is force field  dependent and 
typically provided in  the header of the  master force field 
parameter file.  The default  value of 1.0  is used,  if the 
STRTORUNIT keyword is not given in the force field parameter 
file or the keyfile.

TAPER  [real]     This  keyword allows  modification of  the 
cutoff windows for  nonbonded potential energy interactions. 
The nonbonded terms are smoothly reduced from their standard 
value at the  beginning of the cutoff window to  zero at the 
far  end  of  the window.  The  far  end  of the  window  is 
specified via  the CUTOFF keyword or  its potential function 
specific  variants. The  modifier  value  supplied with  the 
TAPER keyword sets  the beginning of the  cutoff window. The 
modifier can be  given either as an  absolute distance value 
in Angstroms, or  as a fraction between zero and  one of the 
CUTOFF distance.  The default  value in  the absence  of the 
TAPER keyword ranges from 0.65 to 0.9 of the CUTOFF distance 
depending on the type of potential function. The windows are 
implemented  via  polynomial-based switching  functions,  in 
some cases combined with energy shifting.

TAU-PRESSURE   [real]       Sets   the  coupling   time   in 
picoseconds for  the Groningen-style pressure  bath coupling 
used  to  control  the   system  pressure  during  molecular 
dynamics calculations.  A default value  of 2.0 is  used for 
TAU-PRESSURE in the absence of the keyword.

TAU-TEMPERATURE  [real]       Sets  the  coupling   time  in 
picoseconds   for  the   Groningen-style  temperature   bath 
coupling  used  to  control the  system  temperature  during 
molecular dynamics  calculations. A default value  of 0.1 is 
used for TAU-TEMPERATURE in the absence of the keyword.

THERMOSTAT [BERENDSEN/ANDERSEN]      This keyword  selects a 
thermostat algorithm for use  during molecular dynamics. Two 
modifiers are  available, a Berendsen bath  coupling method, 
and an Andersen stochastic  collision method. The default in 
the  absence  of  the  THERMOSTAT  keyword  is  to  use  the 
BERENDSEN algorithm.

TORSION  [4 integers  & up  to 6  real/real/integer triples]     
This  keyword provides  the  values for  a single  torsional 
angle parameter.  The first four integer  modifiers give the 
atom class numbers  for the atoms involved  in the torsional 
angle  to  be defined.  Each  of  the remaining  triples  of 
real/real/integer modifiers  give the  half-amplitude, phase 
offset in degrees and  periodicity of a particular torsional 
function  term, respectively.  Periodicities through  6-fold 
are allowed for torsional parameters.

TORSION4 [4  integers &  up to 6  real/real/integer triples]     
This  keyword provides  the  values for  a single  torsional 
angle parameter  specific to atoms in  4-membered rings. The 
first four integer modifiers give the atom class numbers for 
the atoms involved in the torsional angle to be defined. The 
remaining  triples  of  real number  and  integer  modifiers 
operate as described above for the TORSION keyword.

TORSION5 [4  integers &  up to 6  real/real/integer triples]     
This  keyword provides  the  values for  a single  torsional 
angle parameter  specific to atoms in  5-membered rings. The 
first four integer modifiers give the atom class numbers for 
the atoms involved in the torsional angle to be defined. The 
remaining  triples  of  real number  and  integer  modifiers 
operate as described above for the TORSION keyword.

TORSIONTERM [NONE/ONLY]     This keyword controls use of the 
torsional angle potential  energy term. In the  absence of a 
modifying  option,   this  keyword  turns  on   use  of  the 
potential. The NONE  option turns off use  of this potential 
energy term. The ONLY option  turns off all potential energy 
terms except for this one.

TORSIONUNIT  [real]      Sets  the scale  factor  needed  to 
convert  the energy  value computed  by the  torsional angle 
potential  into units  of  kcal/mole. The  correct value  is 
force field  dependent and typically provided  in the header 
of the master force field  parameter file. The default value 
of 1.0 is  used, if the TORSIONUNIT keyword is  not given in 
the force field parameter file or the keyfile.

TORTORTERM [NONE/ONLY]     This keyword  controls use of the 
torsion-torsion potential  energy term. In the  absence of a 
modifying  option,   this  keyword  turns  on   use  of  the 
potential. The NONE  option turns off use  of this potential 
energy term. The ONLY option  turns off all potential energy 
terms  except  for  this  one.   This  energy  term  is  not 
implemented in the current version of TINKER.

TRIAL-DISTANCE                  [CLASSIC/RANDOM/TRICOR/HAVEL 
integer/PAIRWISE integer]     Sets  the method for selection 
of  a   trial  distance  matrix  during   distance  geometry 
computations. The keyword takes  a modifier that selects the 
method to  be used.  The HAVEL  and PAIRWISE  modifiers also 
require  an  additional  integer value  that  specifies  the 
number of  atoms used in  metrization and the  percentage of 
metrization,  respectively. The  default in  the absence  of 
this keyword is to use  the PAIRWISE method with 100 percent 
metrization. Further  information on the various  methods is 
given with  the description of the  TINKER distance geometry 
program.

TRIAL-DISTRIBUTION [real]     Sets the initial value for the 
mean  of  the Gaussian  distribution  used  to select  trial 
distances between the lower and upper bounds during distance 
geometry computations. The value given must be between 0 and 
1 which  represent the lower and  upper bounds respectively. 
This keyword is  rarely needed since TINKER  will usually be 
able to choose a reasonable value by default.

TRUNCATE      Causes   all  distance-based   nonbond  energy 
cutoffs  to be  sharply truncated  to an  energy of  zero at 
distances  greater   than  the  value  set   by  the  cutoff 
keyword(s)  without  use  of   any  shifting,  switching  or 
smoothing  schemes.  At  all  distances  within  the  cutoff 
sphere, the full interaction energy is computed.

UREY-CUBIC [real]      Sets the value  of the cubic  term in 
the  Taylor  series  expansion   form  of  the  Urey-Bradley 
potential energy.  The real number modifier  gives the value 
of  the   coefficient  as   a  multiple  of   the  quadratic 
coefficient. The default  value in the absence  of the UREY-
CUBIC keyword is zero; i.e.,  the cubic Urey-Bradley term is 
omitted.

UREY-QUARTIC [real]      Sets the value of  the quartic term 
in  the Taylor  series  expansion form  of the  Urey-Bradley 
potential energy.  The real number modifier  gives the value 
of  the   coefficient  as   a  multiple  of   the  quadratic 
coefficient. The default  value in the absence  of the UREY-
QUARTIC keyword is zero; i.e., the quartic Urey-Bradley term 
is omitted.

UREYBRAD [3  integers &  2 reals]     This  keyword provides 
the values  for a  single Urey-Bradley cross  term potential 
parameter. The integer modifiers give the atom class numbers 
for the three kinds of atoms involved in the angle for which 
a  Urey-Bradley  term is  to  be  defined. The  real  number 
modifiers give the force constant value for the term and the 
target value  for the 1-3  distance in Å. The  default units 
for the  force constant  are kcal/mole/Å2,  but this  can be 
controlled via the UREYUNIT keyword.

UREYTERM [NONE/ONLY]      This keyword  controls use  of the 
Urey-Bradley  potential energy  term.  In the  absence of  a 
modifying  option,   this  keyword  turns  on   use  of  the 
potential. The NONE  option turns off use  of this potential 
energy term. The ONLY option  turns off all potential energy 
terms except for this one.

UREYUNIT [real]     Sets the  scale factor needed to convert 
the energy value computed by the Urey-Bradley potential into 
units  of  kcal/mole.  The  correct  value  is  force  field 
dependent and typically provided in the header of the master 
force  field parameter  file. The  default value  of 1.0  is 
used,  if the  UREYUNIT keyword  is not  given in  the force 
field parameter file or the keyfile.

VDW [1 integer  & 3 reals]     This  keyword provides values 
for a single van der  Waals parameter. The integer modifier, 
if  positive, gives  the  atom class  number  for which  vdw 
parameters are to  be defined. Note that  vdw parameters are 
given  for atom  classes,  not atom  types.  The three  real 
number  modifiers give  the values  of the  atom size  in Å, 
homoatomic  well   depth  in  kcal/mole,  and   an  optional 
reduction factor for univalent atoms.

VDW-12-SCALE    [real]       This    keyword   provides    a 
multiplicative scale factor that is applied to van der Waals 
potential  interactions between  1-2 connected  atoms, i.e., 
atoms that are directly bonded.  The default value of 0.0 is 
used, if the VDW-12-SCALE keyword is not given in either the 
parameter file or the keyfile.

VDW-13-SCALE    [real]       This    keyword   provides    a 
multiplicative scale factor that is applied to van der Waals 
potential  interactions between  1-3 connected  atoms, i.e., 
atoms separated by two covalent  bonds. The default value of 
0.0 is  used, if  the VDW-13-SCALE keyword  is not  given in 
either the parameter file or the keyfile.

VDW-14-SCALE    [real]       This    keyword   provides    a 
multiplicative scale factor that is applied to van der Waals 
potential  interactions between  1-4 connected  atoms, i.e., 
atoms separated  by three covalent bonds.  The default value 
of 1.0 is used, if the  VDW-14-SCALE keyword is not given in 
either the parameter file or the keyfile.

VDW-15-SCALE    [real]       This    keyword   provides    a 
multiplicative scale factor that is applied to van der Waals 
potential  interactions between  1-5 connected  atoms, i.e., 
atoms separated by four covalent bonds. The default value of 
1.0 is  used, if  the VDW-15-SCALE keyword  is not  given in 
either the parameter file or the keyfile.

VDW-CUTOFF  [real]     Sets  the  cutoff  distance value  in 
Angstroms for  van der Waals potential  energy interactions. 
The energy  for any pair of  van der Waals sites  beyond the 
cutoff distance will  be set to zero. Other  keywords can be 
used to select a smoothing  scheme near the cutoff distance. 
The default cutoff distance in the absence of the VDW-CUTOFF 
keyword  is infinite  for  nonperiodic systems  and 9.0  for 
periodic systems.

VDW-TAPER [real]     This keyword allows modification of the 
cutoff   windows  for   van  der   Waals  potential   energy 
interactions. It is similar in  form and action to the TAPER 
keyword,  except that  its  value applies  only  to the  vdw 
potential. The default value in the absence of the VDW-TAPER 
keyword  is to begin  the cutoff  window at  0.9 of  the vdw 
cutoff distance.

VDW14 [1 integer & 2 reals]     This keyword provides values 
for  a  single  van  der  Waals parameter  for  use  in  1-4 
nonbonded interactions.  The integer modifier,  if positive, 
gives the atom class number  for which vdw parameters are to 
be  defined. Note  that vdw  parameters are  given for  atom 
classes, not atom types. The  two real number modifiers give 
the values  of the atom  size in  Å and the  homoatomic well 
depth in kcal/mole. Reduction  factors, if used, are carried 
over from the VDW keyword for the same atom class.

VDWPR [2 integers  & 2 reals]     This  keyword provides the 
values  for   the  vdw  parameters  for   a  single  special 
heteroatomic pair  of atoms. The integer  modifiers give the 
pair of atom class numbers  for which special vdw parameters 
are to  be defined. The  two real number modifiers  give the 
values of the  minimum energy contact distance in  Å and the 
well depth at the minimum distance in kcal/mole.

VDWTERM [NONE/ONLY]     This keyword controls use of the van 
der Waals repulsion-dispersion potential energy term. In the 
absence of a modifying option,  this keyword turns on use of 
the  potential.  The  NONE  option turns  off  use  of  this 
potential  energy  term.  The  ONLY  option  turns  off  all 
potential energy terms except for this one.

VDWTYPE    [LENNARD-JONES/BUCKINGHAM/BUFFERED-14-7/MM3-HBOND 
/GAUSSIAN]      Sets the  functional  form for  the van  der 
Waals  potential energy  term. The  text modifier  gives the 
name  of  the  functional  form to  be  used.  The  GAUSSIAN 
modifier value implements a two  or four Gaussian fit to the 
corresponding Lennard-Jones function  for use with potential 
energy smoothing schemes. The default  in the absence of the 
VDWTYPE  keyword  is  to  use  the  standard  two  parameter 
Lennard-Jones function.

VERBOSE     Turns on printing of secondary and informational 
output during a variety of  TINKER computations; a subset of 
the more extensive output provided by the DEBUG keyword.

WALL [real]     Sets the radius of a spherical boundary used 
to maintain  droplet boundary conditions. The  real modifier 
specifies the desired approximate  radius of the droplet. In 
practice, an artificial van der Waals wall is constructed at 
a  fixed buffer  distance  of 2.5  Å  outside the  specified 
radius.  The effect  is  that atoms  which  attempt to  move 
outside the  region defined  by the  droplet radius  will be 
forced toward the center.

WRITEOUT  [integer]     A  general  parameter for  iterative 
procedures  such as  minimizations that  sets the  number of 
iterations between  writes of intermediate results  (such as 
the current coordinates) to  disk file(s). The default value 
in the absence  of the keyword is 1,  i.e., the intermediate 
results  are written  to  file on  every iteration.  Whether 
successive  results  are  saved  to  new  files  or  replace 
previously written intermediate results is controlled by the 
OVERWRITE and SAVECYCLE keywords.
 8.     Notes on Special Features & Methods

     This section contains several  short notes with further 
information about TINKER methodology, algorithms and special 
features. The  discussion is not intended  to be exhaustive, 
but  rather to  explain  features and  capabilities so  that 
users can make more complete use of the package.

FILE VERSION NUMBERS

     All of the  input and output file  types routinely used 
by the  TINKER package are  capable of existing  as multiple 
versions of  a base file  name. For example, if  the program 
XYZINT is  run on  the input  file molecule.xyz,  the output 
internal coordinates  file will be written  to molecule.int. 
If a  file named  molecule.int is  already present  prior to 
running XYZINT, then  the output will be  written instead to 
the next available version,  in this case to molecule.int_2. 
In  fact  the output  is  generally  written to  the  lowest 
available, previously unused version number (molecule.int_3, 
molecule.int_4, etc.,  as high as needed).  Input file names 
are handled similarly. If simply molecule or molecule.xyz is 
entered as the input file name upon running XYZINT, then the 
highest version of  molecule.xyz will be used  as the actual 
input file. If an explicit version number is entered as part 
of the input  file name, then the specified  version will be 
used as the input file.

     The version  number scheme  will be recognized  by many 
older users as a holdover from  the VMS origins of the first 
version of  the TINKER software.  It has been  maintained to 
make it easier to  chain together multiple calculations that 
may create several new versions of a given file, and to make 
it more  difficult to accidently overwrite  a needed result. 
The  version scheme  applies  to most  uses  of many  common 
TINKER file types such as .xyz,  .int, .key, .arc. It is not 
used when  an overwritten  file ``update'' is  obviously the 
correct  action, for  example, the  .dyn molecular  dynamics 
restart files. For  those users who prefer  a more Unix-like 
operation,  and do  not desire  use of  file versions,  this 
feature can be turned off by adding the NOVERSION keyword to 
the applicable TINKER keyfile.

     The version  scheme as implemented in  TINKER does have 
two known  quirks. First, it becomes  impossible to directly 
use  the  original unversioned  copy  of  a file  if  higher 
version  numbers  are present.  For  example,  if the  files 
molecule.xyz   and    molecule.xyz_2   both    exist,   then 
molecule.xyz  cannot  be accessed  as  input  by XYZINT.  If 
molecule.xyz is entered  in response to the  input file name 
question,  molecule.xyz_2 (or  the  highest present  version 
number) will  be used  as input. The  only workaround  is to 
copy  or   rename  molecule.xyz   to  something   else,  say 
molecule.new,  and  use  that   name  for  the  input  file. 
Secondly, missing version numbers  always end the search for 
the highest available version  number; i.e., version numbers 
are assumed to be consecutive and without gaps. For example, 
if  molecule.xyz,  molecule.xyz_2   and  molecule.xyz_4  are 
present, but not molecule.xyz_3, then molecule.xyz_2 will be 
used as  input to XYZINT if  molecule is given as  the input 
file name. Similarly,  output files will fill in  gaps in an 
already existing set of file versions.

COMMAND LINE OPTIONS

     Many operating  systems or  compiler supplied-libraries 
make available  something like  the standard Unix  iargc and 
getarg  routines for  capturing command  line arguments.  On 
these  machines  most  of  the  TINKER  programs  support  a 
selection of command line arguments and options. The name of 
the keyfile  to be used for  a calculation is read  from the 
argument  following a  -k (equivalent  to either  -key or  -
keyfile, case insensitive) command  line argument. Note that 
the  -k options  can  appear anywhere  on  the command  line 
following  the  executable  name.  All  other  command  line 
arguments,  excepting the  name  of  the executable  program 
itself,  are   treated  as  input  arguments.   These  input 
arguments are  read from  left to  right and  interpreted in 
order as the answers to questions  that would be asked by an 
interactive  invocation  of  the same  TINKER  program.  For 
example, the following command line:

newton molecule -k test a a 0.01

will  invoke  the  NEWTON  program  on  the  structure  file 
molecule.xyz using the keyfile  test.key, automatic mode [a] 
for both  the method and  preconditioning, and 0.01  for the 
RMS gradient per atom  termination criterion in kcal/mole/Å. 
Provided  that  the  force  field  parameter  set,  etc.  is 
provided  in test.key,  the  above  compuation will  procede 
directly from  the command  line invocation  without further 
interactive input.

USE ON MICROSOFT WINDOWS SYSTEMS

     TINKER executables  for Microsoft PC systems  should be 
run from the  DOS Prompt window available  under the various 
versions of Windows. The  TINKER executable directory should 
be added to your path  via the autoexec.bat file or similar. 
If using Win2000, set the  number of scrollable lines in the 
DOS Prompt window  to a very large number, so  that you will 
be able  to inspect  screen output after  it flies  by. With 
Win95/98, these DOS Prompt windows are only able to scroll a 
small number  of lines (amazing!), so  TINKER programs which 
generate large amounts  of screen output should  be run such 
that  output will  be  redirected  to a  file.  This can  be 
accomplished by running the TINKER  program in batch mode or 
by using  the Unix-like  output redirection build  into DOS. 
For example, the command:

dynamic < molecule.inp > molecule.log

will run  the TINKER dynamic  program taking input  from the 
file molecule.inp  and sending output to  molecule.log. Also 
note  that  command  line  options as  described  above  are 
available with the distributed TINKER executables.

     Another alternative,  particularly attractive  to those 
already familiar with Linux or  Unix systems, is to download 
the  Cygwin package  currently available  under GPL  license 
from the  site http://source.redhat.com/cygwin/.  The cygwin 
tools provide many of the  GNU tools, including a bash shell 
window from which TINKER programs can be run.

     If the distributed TINKER executables are directly from 
Windows by  double clicking  on the  program icon,  then the 
program will run in its own window. However, upon completion 
of the program the window  will close and screen output will 
be lost.  Any output files  written by the program  will, of 
course,  still be  available.  The Windows  behavior can  be 
changed by adding the EXIT-PAUSE keyword to the keyfile.

USE ON APPLE MACINTOSH SYSTEMS

     The TINKER executables can be run under MacOS by double 
clicking on a program icon. The  program will run in its own 
window to which all ``screen'' output will be directed. Upon 
program termination the window  will remain active pending a 
final  return  entered by  the  user  which will  close  the 
window.  Prior to  the  final return,  the  contents of  the 
screen window can  be saved to a file via  the clipboard for 
permanent storage. Note that  Macintosh uses a colon instead 
of a forward-  or back-slash as the  directory separator, so 
keyfiles  transfered from  other  machines will  need to  be 
altered accordingly.

ATOM TYPES VS. ATOM CLASSES

     Manipulation  of atom  types and  the proliferation  of 
parameters as atoms are further subdivided into new types is 
the bane  of force field  calculation. For example,  if each 
topologically  distinct atom  arising  from  the 20  natural 
amino acids is  given a different atom type,  then about 300 
separate type  are required  (this ignores the  different N- 
and  C-terminal   forms  of  the   residues,  diastereotopic 
hydrogens, etc.). However, all these types lead to literally 
thousands  of different  force  field  parameters. In  fact, 
there are  many thousands  of distinct  torsional parameters 
alone. It is impossible at present to fully optimize each of 
these parameters; and even if we  could, a great many of the 
parameters   would  be   nearly   identical.  Two   somewhat 
complimentary   solutions  are   available  to   handle  the 
proliferation  of parameters.  The first  is to  specify the 
molecular  fragments  to  which  a given  parameter  can  be 
applied in  terms of  a chemical structure  language, SMILES 
strings for  example. Some  commercial systems, such  as the 
TRIPOS Sybyl  software, make use  of such a scheme  to parse 
structures and assign force field parameters.

     A  second  general  approach  is  to  use  hierarchical 
cascades of  parameter groups. TINKER uses  a simple version 
of this  scheme. Each  TINKER force field  atom has  both an 
atom type  number and  an atom class  number. The  types are 
subsets of  the atom  classes, i.e., several  different atom 
types  can  belong  to  the same  atom  class.  Force  field 
parameters  that  are  somewhat   less  sensitive  to  local 
environment, such as local geometry terms, are then provided 
and assigned  based on atom class.  Other energy parameters, 
such as electrostatic parameters,  that are very environment 
dependent  are assigned  over the  atom types.  This greatly 
reduces the  number of independent  multiple-atom parameters 
like the four-atom torsional parameters.

CALCULATIONS ON PARTIAL STRUCTURES

     Two  methods  are  available for  performing  energetic 
calculations  on portions  or  substructures  within a  full 
molecular  system.  TINKER  allows division  of  the  entire 
system into active  and inactive parts which  can be defined 
via   keywords.   In   subsequent  calculations,   such   as 
minimization or  dynamics, only  the active portions  of the 
system are allowed to move.  The force field engine responds 
to the  active/inactive division by computing  all energetic 
interactions involving  at least one active  atom; i.e., any 
interaction whose energy  can change with the  motion of one 
or more active atoms is computed.

     The  second method  for  partial structure  computation 
involves dividing  the original  system into  a set  of atom 
groups.  As   before,  the  groups  can   be  specified  via 
appropriate  keywords.  The  current  TINKER  implementation 
allows specification of up to  a maximum number of groups as 
given in the  sizes.i dimensioning file. The  groups must be 
disjoint in that no atom can  belong to more than one group. 
Further keywords allow the user  to specify which intra- and 
intergroup sets of energetic interactions will contribute to 
the  total  force field  energy.  Weights  for each  set  of 
interactions  in  the total  energy  can  also be  input.  A 
specific energetic  interaction is assigned to  a particular 
intra- or  intergroup set if  all the atoms involved  in the 
interaction belong to  the group (intra-) or  pair of groups 
(inter-). Interactions  involving atoms  from more  than two 
groups are not computed.

     Note that the groups  method and active/inactive method 
use   different   assignment   procedures   for   individual 
interactions.  The active/inactive  scheme  is intended  for 
situations where  only a portion  of a system is  allowed to 
move, but the total energy  needs to reflect the presence of 
the remaining inactive portion  of the structure. The groups 
method is intended  for use in rigid  body calculations, and 
is  needed for  certain  kinds of  free energy  perturbation 
calculations.

METAL COMPLEXES AND HYPERVALENT SPECIES

     The  distribution version  of TINKER  comes dimensioned 
for a maximum  atomic coordination number of  four as needed 
for standard organic  compounds. In order to  use TINKER for 
calculations  on  species   containing  higher  coordination 
numbers, simply change the value  of the parameter maxval in 
the  master  dimensioning  file   sizes.i  and  rebuilt  the 
package. Note  that this parameter  value should not  be set 
larger  than  necessary  since  large values  can  slow  the 
execution of portions of some TINKER programs.

     Many  molecular mechanics  approaches to  inorganic and 
metal structures use  an angle bending term  which is softer 
than the usual harmonic bending potential. TINKER implements 
a Fourier  bending term similar  to that used by  the Landis 
group's  SHAPES force  field.  The  parameters for  specific 
Fourier angle  terms are  supplied via the  ANGLEF parameter 
and keyword  format. Note that  a Fourier term will  only be 
used  for a  particular  angle if  a corresponding  harmonic 
angle term is not present in the parameter file.

     We are  now collaborating with Anders  Carlsson's group 
in St. Louis  to add his transition metal  ligand field term 
to TINKER. Support for  this additional potential functional 
form is  already in the TINKER  source code, and we  plan to 
release  the  energy  routines  after  further  testing  and 
parameterization.

NEIGHBOR METHODS FOR NONBONDED TERMS

     In addition to standard double loop methods, the Method 
of  Lights is  available to  speed neighbor  searching. This 
method based  on taking  intersections of sorted  atom lists 
can be much faster for problems where the cutoff distance is 
significantly smaller than half  the maximal cell dimension. 
The  current  version  of  TINKER  does  not  implement  the 
``neighbor list''  schemes common  to many  other simulation 
packages.

PERIODIC BOUNDARY CONDITIONS

     Both spherical  cutoff images  or replicates of  a cell 
are supported by all TINKER programs that implement periodic 
boundary  conditions. Whenever  the cutoff  distance is  too 
large for the minimum image to be the only relevant neighbor 
(i.e., half the minimum box dimension for orthogonal cells), 
TINKER will automatically switch from the image formalism to 
use of replicated cells.

DISTANCE CUTOFFS FOR ENERGY FUNCTIONS

     Polynomial energy  switching over a window  is used for 
terms whose  energy is small  near the cutoff  distance. For 
monopole electrostatic  interactions, which are  quite large 
in typical  cutoff ranges, a two  polynomial multiplicative-
additive shifted energy switch  unique to TINKER is applied. 
The  TINKER  method  is  similar  in  spirit  to  the  force 
switching methods of Steinbach and Brooks, J. Comput. Chem., 
15, 667-683 (1994). While the  particle mesh Ewald method is 
preferred  when periodic  boundary  conditions are  present, 
TINKER's  shifted energy  switch  with reasonable  switching 
windows  is quite  satisfactory  for  most routine  modeling 
problems.   The   shifted   energy  switch   minimizes   the 
perturbation of the energy and the gradient at the cutoff to 
acceptable  levels.  Problems  should   arise  only  if  the 
property you  wish to monitor  is known to  require explicit 
inclusion of long range components (i.e., calculation of the 
dielectric constant, etc.).

EWALD SUMMATION METHODS

     TINKER  contains  a  versions of  the  Ewald  summation 
technique   for  inclusion   of  long   range  electrostatic 
interactions  via  periodic  boundaries. The  particle  mesh 
Ewald  (PME) method  is available  for simple  charge-charge 
potentials, while regular Ewald  is provided for polarizable 
atomic multipole interactions. The accuracy and speed of the 
regular  and  PME  calculations   is  dependent  on  several 
interrelated  parameters.   For  both  methods,   the  Ewald 
coefficient and  real-space cutoff  distance must be  set to 
reasonable  and  complementary  values.  Additional  control 
variables for regular Ewald  are the fractional coverage and 
number  of vectors  used in  reciprocal space.  For PME  the 
additional control values are  the B-spline order and charge 
grid  dimensions.   Complete  control  over  all   of  these 
parameters is available via the TINKER keyfile mechanism. By 
default TINKER will select a set of parameters which provide 
a  reasonable compromise  between  accuracy  and speed,  but 
these should be  checked and modified as  necessary for each 
individual system.

CONTINUUM SOLVATION MODELS

     Several alternative continuum  solvation algorithms are 
contained within TINKER.  All of these are  accessed via the 
SOLVATE keyword  and its modifiers. Two  simple surface area 
methods  are implemented:  the ASP  method of  Eisenberg and 
McLachlan, and the SASA  method from Scheraga's group. These 
methods are applicable  to any of the  standard TINKER force 
fields.  Various  schemes  based  on  the  generalized  Born 
formalism are  also available:  the original  1990 numerical 
``Onion-shell'' GB/SA  method from  Still's group,  the 1997 
analytical  GB/SA  method  also  due to  Still,  a  pairwise 
descreening algorithm originally proposed by Hawkins, Cramer 
and Truhlar,  and the  analytical continuum  solvation (ACE) 
method of Schaefer and  Karplus. At present, the generalized 
Born methods  should only be  used with force  fields having 
simple partial charge electrostatic interactions.

     Some further comments are in order regarding the GB/SA-
style  solvation   models.  The  ``Onion-shell''   model  is 
provided mostly  for comparison purposes. It  uses an exact, 
analytical surface area calculation  for the cavity term and 
the numerical scheme described in the original paper for the 
polarization term. This method  is very slow, especially for 
large systems, and does not  contain the contribution of the 
Born  radii chain  rule term  to the  first derivatives.  We 
recommend its use only for single-point energy calculations. 
The  other   GB/SA  methods  (``analytical''   Still,  H-C-T 
pairwise  descreening, and  ACE) use  an approximate  cavity 
term  based on  Born  radii, and  do  contain fully  correct 
derivatives   including   the    Born   radii   chain   rule 
contribution. These methods  all scale in CPU  time with the 
square  of the  size of  the system,  and can  be used  with 
minimization, molecular dynamics and large molecules.

     Finally, we  note that  the ACE solvation  model should 
not  be  used  with  the  current  version  of  TINKER.  The 
algorithm  is  fully implemented  in  the  source code,  but 
parameterization is not complete. As of late 2000, parameter 
values are only  available in the literature for  use of ACE 
with  the older  CHARMM19 force  field. We  plan to  develop 
values for use  with more modern all-atom  force fields, and 
these  will  be incorporated  into  TINKER  sometime in  the 
future.

POLARIZABLE MULTIPOLE ELECTROSTATICS

     Atomic multipole electrostatics  through the quadrupole 
moment is supported by the  current version of TINKER, as is 
either mutual or direct dipole polarization. Ewald summation 
is  available  for  inclusion of  long  range  interactions. 
Calculations  are  implemented via  a  mixture  of the  CCP5 
algorithms of W. Smith  and the Applequist-Dykstra Cartesian 
polytensor   method.  At   present  analytical   energy  and 
Cartesian gradient code is provided.

     The TINKER  package allows  intramolecular polarization 
to  be treated  via  a version  of  the interaction  damping 
scheme  of  Thole. To  implement  the  Thole scheme,  it  is 
necessary to set all the mutual-1x-scale keywords to a value 
of  one.  The  other polarization  scaling  keyword  series, 
direct-1x-scale and polar-1x-scale, can be set independently 
to enable a wide variety of polarization models. In order to 
use an Applequist-style  model without polarization damping, 
simply set the polar-damp keyword to zero.

POTENTIAL ENERGY SMOOTHING

     Versions of  our Potential  Smoothing and  Search (PSS) 
methodology  have  been   implemented  within  TINKER.  This 
methods  belong to  the  same general  family as  Scheraga's 
Diffusion   Equation  Method,   Straub's  Gaussian   Density 
Annealing,  Shalloway's  Packet Annealing  and  Verschelde's 
Effective Diffused Potential, but our algorithms reflect our 
own ongoing research  in this area. In many  ways the TINKER 
potential smoothing methods are  the deterministic analog of 
stochastic simulated annealing. The  PSS algorithms are very 
powerful, but  are relatively  new and are  still undergoing 
modification,  testing and  calibration within  our research 
group. This version of  TINKER also includes a basin-hopping 
conformational scanning algorithm in  the program SCAN which 
is particularly effective on smoothed potential surfaces.

DISTANCE GEOMETRY METRIZATION

     A  much   improved  and   very  fast   random  pairwise 
metrization scheme  is available which allows  good sampling 
during trial  distance matrix  generation without  the usual 
structural   anomalies   and   CPU  constraints   of   other 
metrization procedures.  An outline  of the  methodology and 
its  application to  NMR NOE-based  structure refinement  is 
described in the paper by Hodsdon,  et al. in J. Mol. Biol., 
264,  585-602 (1996).  We  have obtained  good results  with 
something   like  the   keyword  phrase   trial-distribution 
pairwise  5,  which  performs  5%  partial  random  pairwise 
metrization. For  structures over  several hundred  atoms, a 
value less than  5 for the percentage  of metrization should 
be fine.

 9.     Descriptions of TINKER Routines

     The distribution version of the TINKER package contains 
over 600 separate programs,  subroutines and functions. This 
section contains a brief description  of the purpose of most 
of these code units. Further information can be found in the 
comments located at the top of each source code file.

ACTIVE Subroutine

"active" sets  the list of  atoms that are used  during each 
potential energy function calculation

ADDBASE Subroutine

"addbase"  builds the  Cartesian  coordinates  for a  single 
nucleic  acid base;  coordinates are  read from  the Protein 
Data Bank file or found from internal coordinates, then atom 
types are assigned and connectivity data generated

ADDBOND Subroutine

"addbond" adds entries  to the attached atoms  list in order 
to generate a direct connection between two atoms

ADDSIDE Subroutine

"addside"  builds the  Cartesian  coordinates  for a  single 
amino acid side chain; coordinates are read from the Protein 
Data Bank file or found from internal coordinates, then atom 
types are assigned and connectivity data generated

ADJACENT Function

"adjacent" finds an  atom connected to atom  "i1" other than 
atom "i2"; if no such atom  exists, then the closest atom in 
space is returned

ALCHEMY Program

"alchemy" computes the  free energy difference corresponding 
to a small perturbation by Boltzmann weighting the potential 
energy difference  over a  number of sample  states; current 
version  (incorrectly) considers  the  charge  energy to  be 
intermolecular in finding the perturbation energies

ANALYSIS Subroutine

"analysis" calls the series  of routines needed to calculate 
the  potential   energy  and  perform   energy  partitioning 
analysis in terms of type of interaction or atom number

ANALYZ4 Subroutine

"analyz4" prints the  energy to 4 decimal  places and number 
of interactions for each component of the potential energy

ANALYZ6 Subroutine

"analyz6" prints the  energy to 6 decimal  places and number 
of interactions for each component of the potential energy

ANALYZ8 Subroutine

"analyz8" prints the  energy to 8 decimal  places and number 
of interactions for each component of the potential energy

ANALYZE Program

"analyze" computes and displays the total potential; options 
are provided to partition the energy by atom or by potential 
function type; parameters used in computing interactions can 
also  be   displayed  by   atom;  output  of   large  energy 
interactions and of electrostatic and inertial properties is 
available

ANGLES Subroutine

"angles" finds  the total number  of bond angles  and stores 
the atom numbers of the  atoms defining each angle; for each 
angle to a tricoordinate central atom, the third bonded atom 
is stored for use in out-of-plane bending

ANNEAL Program

"anneal" performs a simulated annealing protocol by means of 
variable temperature molecular dynamics using either linear, 
exponential or sigmoidal cooling schedules

ANORM Function

"anorm"  finds the  norm (length)  of  a vector;  used as  a 
service  routine by  the  Connolly surface  area and  volume 
computation

ARCHIVE Program

"archive" is  a utility  program for coordinate  files which 
concatenates multiple coordinate sets  into a single archive 
file, or extracts individual coordinate sets from an archive

ASET Subroutine

ATOMYZE Subroutine

"atomyze" prints the potential energy components broken down 
by atom and to a choice of precision

ATTACH Subroutine

"attach" generates lists of  1-3, 1-4 and 1-5 connectivities 
starting  from the  previously determined  list of  attached 
atoms (ie, 1-2 connectivity)

BASEFILE Subroutine

"basefile"  extracts  from  an input  filename  the  portion 
consisting of any directory name and the base filename

BEEMAN Subroutine

"beeman" performs  a single molecular dynamics  time step by 
means of  a Beeman  multistep recursion formula;  the actual 
coefficients are Brooks' "Better Beeman" values

BETACF Function

"betacf"  computes a  rapidly convergent  continued fraction 
needed by  routine "betai"  to evaluate the  cumulative Beta 
distribution

BETAI Function

"betai" evaluates the  cumulative Beta distribution function 
as   the  probability   that  a   random  variable   from  a 
distribution with Beta  parameters "a" and "b"  will be less 
than "x"

BIGBLOCK Subroutine

"bigblock" replicates the coordinates  of a single unit cell 
to give a larger block of repeated units

BMAX Function

BNDERR Function

"bnderr"   is  the   distance  bound   error  function   and 
derivatives;  this  version   implements  the  original  and 
Havel's  normalized  lower  bound  penalty,  the  normalized 
version is  preferred when lower  bounds are small  (as with 
NMR NOE restraints), the original penalty is needed if large 
lower bounds are present

BONDS Subroutine

"bonds" finds the total number  of covalent bonds and stores 
the atom numbers of the atoms defining each bond

BORN Subroutine

"born" computes  the Born radius  of each atom for  use with 
the various GB/SA solvation models

BORN1 Subroutine

"born1" computes derivatives of  the Born radii with respect 
to   atomic   coordinates   and  increments   total   energy 
derivatives and  virial components for  potentials involving 
Born radii

BOUNDS Subroutine

"bounds"  finds  the  center   of  mass  of  each  molecule, 
translates any  stray molecules back into  the periodic box, 
and saves the offset of  each atom relative to the molecular 
center of mass

BSET Subroutine

BSPLINE Subroutine

"bspline" calculates  the coefficients for an  n-th order B-
spline approximation

BSPLINE1 Subroutine

"bspline1"  calculates   the  coefficients   and  derivative 
coefficients for an n-th order B-spline approximation

BSSTEP Subroutine

CALENDAR Subroutine

"calendar"  returns the  current time  as a  set of  integer 
values representing  the year, month, day,  hour, minute and 
second

CELLATOM Subroutine

"cellatom" completes the addition of a symmetry related atom 
to  a unit  cell by  updating the  atom type  and attachment 
arrays

CENTER Subroutine

"center" moves the weighted  centroid of each coordinate set 
to the origin during least squares superposition

CERROR Subroutine

"cerror"  is the  error  handling routine  for the  Connolly 
surface area and volume computation

CFFTB Subroutine

"cfftb"  computes  the  backward  complex  discrete  Fourier 
transform, the Fourier synthesis

CFFTB1 Subroutine

CFFTF Subroutine

"cfftf"  computes  the   forward  complex  discrete  Fourier 
transform, the Fourier analysis

CFFTF1 Subroutine

CFFTI Subroutine

"cffti" initializes the array "wsave"  which is used in both 
forward and backward transforms;  the prime factorization of 
"n"  together   with  a  tabulation  of   the  trigonometric 
functions are computed and stored in "wsave"

CFFTI1 Subroutine

CHIRER Function

"chirer" computes  the chirality  error and  its derivatives 
with respect  to atomic Cartesian  coordinates as a  sum the 
squares of deviations of chiral volumes from target values

CHKSIZE Subroutine

"chksize" computes  a measure  of overall  global structural 
expansion or compaction  from the number of  excess upper or 
lower bounds matrix violations

CHKTREE Subroutine

"chktree"  tests a  minimum energy  structure to  see if  it 
belongs to the correct progenitor in the existing map

CHKXYZ Subroutine

"chkxyz" finds  any pairs of atoms  with identical Cartesian 
coordinates, and prints a warning message

CHOLESKY Subroutine

"cholesky"  uses a  modified  Cholesky method  to solve  the 
linear system Ax  = b, returning "x" in "b";  "A" is assumed 
to  be  a  real  symmetric  positive  definite  matrix  with 
diagonal and upper triangle stored  by rows in "A"; thus the 
actual size of the passed portion of "A" is nvar*(nvar+1)/2

CIRPLN Subroutine

CJKM Function

CLIMBER Subroutine

CLIMBRGD Subroutine

CLIMBROT Subroutine

CLIMBTOR Subroutine

CLIMBXYZ Subroutine

CLOCK Subroutine

"clock"  determines elapsed  CPU time  in seconds  since the 
start of the job

CLUSTER Subroutine

"cluster" gets  the partitioning  of the system  into groups 
and stores a list of the group to which each atom belongs

COLUMN Subroutine

"column" takes  the off-diagonal Hessian elements  stored as 
sparse rows and sets up indices to allow column access

COMMAND Subroutine

"command" uses the  standard Unix-like iargc/getarg routines 
to get the  number and values of arguments  specified on the 
command line at program runtime

COMPRESS Subroutine

"compress"  transfers  only  the non-buried  tori  from  the 
temporary tori arrays to the final tori arrays

CONNECT Subroutine

"connect" sets up  the attached atom arrays  starting from a 
set of internal coordinates

CONNOLLY Subroutine

"connolly" uses the algorithms  from the AMS/VAM programs of 
Michael Connolly to compute the analytical molecular surface 
area and volume of a  collection of spherical atoms; thus it 
implements Fred Richards' molecular  surface definition as a 
set of analytically defined spherical and toroidal polygons

CONTACT Subroutine

"contact" constructs the contact  surface, cycles and convex 
faces

CONTROL Subroutine

"control" gets initial values  for parameters that determine 
the output style and information level provided by TINKER

COORDS Subroutine

"coords"  converts the  three principal  eigenvalues/vectors 
from the metric matrix into  atomic coordinates, and calls a 
routine to compute the rms deviation from the bounds

CORRELATE Program

"correlate" computes  the time correlation function  of some 
user-supplied property from individual snapshot frames taken 
from a molecular dynamics or other trajectory

CRYSTAL Program

"crystal"  is  a  utility  program  which  converts  between 
fractional and Cartesian coordinates,  and can generate full 
unit cells from asymmetric units

CUTOFFS Subroutine

"cutoffs"  initializes and  stores  spherical energy  cutoff 
distance windows, Hessian element and Ewald sum cutoffs, and 
the pairwise neighbor generation method

D1D2 Function

DELETE Subroutine

"delete"  removes  a  specified   atom  from  the  Cartesian 
coordinates list and shifts the remaining atoms

DEPTH Function

DFTMOD Subroutine

"dftmod"  computes  the  modulus  of  the  discrete  Fourier 
transform of "bsarray", storing it into "bsmod"

DIAGQ Subroutine

"diagq" is a matrix diagonalization routine which is derived 
from the classical given,  housec, and eigen algorithms with 
several  modifications   to  increase  the   efficiency  and 
accuracy

DIFFEQ Subroutine

"diffeq" performs  the numerical integration of  an ordinary 
differential equation  using an adaptive stepsize  method to 
solve the corresponding coupled first-order equations of the 
general form dyi/dx = f(x,y1,...,yn) for yi = y1,...,yn

DIFFUSE Program

"diffuse"   finds   the   self-diffusion  constant   for   a 
homogeneous liquid via  the Einstein relation from  a set of 
stored molecular dynamics frames;  molecular centers of mass 
are  unfolded and  mean squared  displacements are  computed 
versus time separation

DIST2 Function

"dist2" finds the distance  squared between two points; used 
as a service routine by the Connolly surface area and volume 
computation

DISTGEOM Program

"distgeom" uses a metric  matrix distance geometry procedure 
to generate  structures with  interpoint distances  that lie 
within specified  bounds, with chiral centers  that maintain 
chirality, and  with torsional angles restrained  to desired 
values;  the  user also  has  the  ability to  interactively 
inspect and alter the  triangle smoothed bounds matrix prior 
to embedding

DMDUMP Subroutine

"dmdump"  puts the  distance matrix  of the  final structure 
into the upper  half of a matrix, the distance  of each atom 
to the centroid on the diagonal, and the individual terms of 
the bounds errors into the lower half of the matrix

DOCUMENT Program

"document" generates a formatted description of all the code 
modules or common blocks, a listing of all valid keywords, a 
list of include file dependencies  as needed by a Unix-style 
Makefile, or a formatted force field parameter set summary

DOT Function

"dot" finds the dot product of two vectors

DSTMAT Subroutine

"dstmat" selects a distance matrix containing values between 
the previously smoothed upper and lower bounds; the distance 
values are chosen from  uniform distributions, in a triangle 
correlated fashion, or using random partial metrization

DYNAMIC Program

"dynamic" computes a molecular dynamics trajectory in any of 
several  statistical  mechanical   ensembles  with  optional 
periodic boundaries and optional coupling to temperature and 
pressure   baths   alternatively   a   stochastic   dynamics 
trajectory can be generated

EANGANG Subroutine

"eangang" calculates the angle-angle potential energy

EANGANG1 Subroutine

"eangang1" calculates  the angle-angle potential  energy and 
first derivatives with respect to Cartesian coordinates

EANGANG2 Subroutine

"eangang2"  calculates  the   angle-angle  potential  energy 
second  derivatives with  respect  to Cartesian  coordinates 
using finite difference methods

EANGANG2A Subroutine

"eangang2a" calculates the angle-angle first derivatives for 
a single interaction with  respect to Cartesian coordinates; 
used in computation of finite difference second derivatives

EANGANG3 Subroutine

"eangang3" calculates the angle-angle potential energy; also 
partitions the energy among the atoms

EANGLE Subroutine

"eangle"  calculates  the  angle bending  potential  energy; 
projected  in-plane angles  at trigonal  centers or  Fourier 
angle bending terms are optionally used

EANGLE1 Subroutine

"eangle1" calculates the angle  bending potential energy and 
the first derivatives with respect to Cartesian coordinates; 
projected  in-plane angles  at trigonal  centers or  Fourier 
angle bending terms are optionally used

EANGLE2 Subroutine

"eangle2" calculates second derivatives of the angle bending 
energy for a  single atom using a mixture  of analytical and 
finite  difference  methods;  projected in-plane  angles  at 
trigonal  centers   or  Fourier  angle  bending   terms  are 
optionally used

EANGLE2A Subroutine

"eangle2a"  calculates bond  angle bending  potential energy 
second derivatives with respect to Cartesian coordinates

EANGLE2B Subroutine

"eangle2b"   computes  projected   in-plane  bending   first 
derivatives  for a  single angle  with respect  to Cartesian 
coordinates; used in computation of finite difference second 
derivatives

EANGLE3 Subroutine

"eangle3"  calculates the  angle  bending potential  energy, 
also partitions  the energy  among the atoms;  projected in-
plane angles  at trigonal  centers or Fourier  angle bending 
terms are optionally used

EBOND Subroutine

"ebond" calculates the bond stretching energy

EBOND1 Subroutine

"ebond1"  calculates the  bond stretching  energy and  first 
derivatives with respect to Cartesian coordinates

EBOND2 Subroutine

"ebond2"   calculates  second   derivatives   of  the   bond 
stretching energy for a single atom at a time

EBOND3 Subroutine

"ebond3"  calculates   the  bond  stretching   energy;  also 
partitions the energy among the atoms

EBUCK Subroutine

"ebuck" calculates the Buckingham exp-6 van der Waals energy

EBUCK0A Subroutine

"ebuck0a"  calculates the  Buckingham  exp-6  van der  Waals 
energy using a pairwise double loop

EBUCK0B Subroutine

"ebuck0b"  calculates the  Buckingham  exp-6  van der  Waals 
energy  using the  method  of lights  to locate  neighboring 
atoms

EBUCK1 Subroutine

"ebuck1"  calculates  the  Buckingham exp-6  van  der  Waals 
energy and  its first derivatives with  respect to Cartesian 
coordinates

EBUCK1A Subroutine

"ebuck1a"  calculates the  Buckingham  exp-6  van der  Waals 
energy and  its first derivatives with  respect to Cartesian 
coordinates using a pairwise double loop

EBUCK1B Subroutine

"ebuck1b"  calculates the  Buckingham  exp-6  van der  Waals 
energy and  its first derivatives with  respect to Cartesian 
coordinates using the method of lights to locate neighboring 
atoms

EBUCK2 Subroutine

"ebuck2"  calculates  the  Buckingham exp-6  van  der  Waals 
second derivatives for a single atom at a time

EBUCK3 Subroutine

"ebuck3"  calculates  the  Buckingham exp-6  van  der  Waals 
energy and partitions the energy among the atoms

EBUCK3A Subroutine

"ebuck3a"  calculates the  Buckingham  exp-6  van der  Waals 
energy and  partitions the  energy among  the atoms  using a 
pairwise double loop

EBUCK3B Subroutine

"ebuck3b"  calculates the  Buckingham  exp-6  van der  Waals 
energy and also partitions the  energy among the atoms using 
the method of lights to locate neighboring atoms

ECHARGE Subroutine

"echarge" calculates the charge-charge interaction energy

ECHARGE0A Subroutine

"echarge0a" calculates the  charge-charge interaction energy 
using a pairwise double loop

ECHARGE0B Subroutine

"echarge0b" calculates the  charge-charge interaction energy 
using the method of lights to locate neighboring atoms

ECHARGE0C Subroutine

"echarge0c" calculates the  charge-charge interaction energy 
for use with potential smoothing methods

ECHARGE0D Subroutine

"echarge0d" calculates the  charge-charge interaction energy 
using a particle mesh Ewald summation

ECHARGE1 Subroutine

"echarge1" calculates  the charge-charge  interaction energy 
and first derivatives with respect to Cartesian coordinates

ECHARGE1A Subroutine

"echarge1a" calculates the  charge-charge interaction energy 
and first derivatives with  respect to Cartesian coordinates 
using a pairwise double loop

ECHARGE1B Subroutine

"echarge1b" calculates the  charge-charge interaction energy 
and first derivatives with  respect to Cartesian coordinates 
using the method of lights to locate neighboring atoms

ECHARGE1C Subroutine

"echarge1c" calculates the  charge-charge interaction energy 
and first derivatives with  respect to Cartesian coordinates 
for use with potential smoothing methods

ECHARGE1D Subroutine

"echarge1d" calculates the  charge-charge interaction energy 
and first derivatives with  respect to Cartesian coordinates 
using a particle mesh Ewald summation

ECHARGE2 Subroutine

"echarge2"  calculates  second  derivatives of  the  charge-
charge interaction energy for a single atom

ECHARGE2A Subroutine

"echarge2a"  calculates second  derivatives  of the  charge-
charge interaction energy for a single atom using a pairwise 
double loop

ECHARGE2B Subroutine

"echarge2b"  calculates second  derivatives  of the  charge-
charge interaction  energy for  a single  atom for  use with 
potential smoothing methods

ECHARGE2C Subroutine

"echarge2c"  calculates second  derivatives  of the  charge-
charge interaction energy for a single atom using a particle 
mesh Ewald summation

ECHARGE3 Subroutine

"echarge3" calculates  the charge-charge  interaction energy 
and partitions the energy among the atoms

ECHARGE3A Subroutine

"echarge3a" calculates the  charge-charge interaction energy 
and partitions the  energy among the atoms  using a pairwise 
double loop

ECHARGE3B Subroutine

"echarge3b" calculates the  charge-charge interaction energy 
and partitions the  energy among the atoms  using the method 
of lights to locate neighboring atoms

ECHARGE3C Subroutine

"echarge3c" calculates the  charge-charge interaction energy 
and  partitions the  energy  among the  atoms  for use  with 
potential smoothing methods

ECHARGE3D Subroutine

"echarge3d" calculates the  charge-charge interaction energy 
and partitions the  energy among the atoms  using a particle 
mesh Ewald summation

ECHGDPL Subroutine

"echgdpl" calculates the charge-dipole interaction energy

ECHGDPL1 Subroutine

"echgdpl1" calculates  the charge-dipole  interaction energy 
and first derivatives with respect to Cartesian coordinates

ECHGDPL2 Subroutine

"echgdpl2"  calculates  second  derivatives of  the  charge-
dipole interaction energy for a single atom

ECHGDPL3 Subroutine

"echgdpl3" calculates the  charge-dipole interaction energy; 
also partitions the energy among the atoms

EDIPOLE Subroutine

"edipole" calculates the dipole-dipole interaction energy

EDIPOLE1 Subroutine

"edipole1" calculates  the dipole-dipole  interaction energy 
and first derivatives with respect to Cartesian coordinates

EDIPOLE2 Subroutine

"edipole2"  calculates  second  derivatives of  the  dipole-
dipole interaction energy for a single atom

EDIPOLE3 Subroutine

"edipole3" calculates the  dipole-dipole interaction energy; 
also partitions the energy among the atoms

EGAUSS Subroutine

"egauss"  calculates the  Gaussian expansion  van der  Waals 
interaction energy

EGAUSS1 Subroutine

"egauss1" calculates  the Gaussian  expansion van  der Waals 
interaction energy and its first derivatives with respect to 
Cartesian coordinates

EGAUSS2 Subroutine

"egauss2" calculates  the Gaussian  expansion van  der Waals 
second derivatives for a single atom at a time

EGAUSS3 Subroutine

"egauss3" calculates  the Gaussian  expansion van  der Waals 
interaction energy and partitions the energy among the atoms

EGBSA0A Subroutine

"egbsa0a"  calculates  the   generalized  Born  polarization 
energy for the GB/SA and ACE solvation models

EGBSA0B Subroutine

"egbsa0b"  calculates  the   generalized  Born  polarization 
energy for the  GB/SA and ACE solvation models  for use with 
potential smoothing methods via  analogy to the smoothing of 
Coulomb's law

EGBSA1A Subroutine

"egbsa1a" calculates  the generalized Born energy  and first 
derivatives with  respect to  Cartesian coordinates  for the 
GB/SA solvation models

EGBSA1B Subroutine

"egbsa1b" calculates  the generalized Born energy  and first 
derivatives with  respect to  Cartesian coordinates  for the 
GB/SA solvation models

EGBSA2A Subroutine

"egbsa2a" calculates  second derivatives of  the generalized 
Born energy term for the GB/SA solvation models

EGBSA2B Subroutine

"egbsa2b" calculates  second derivatives of  the generalized 
Born energy term for the  GB/SA solvation models via analogy 
to the smoothing of Coulomb's law

EGBSA3A Subroutine

"egbsa3a" calculates  the generalized  Born energy  term for 
the  GB/SA and  ACE  solvation models;  also partitions  the 
energy among the atoms

EGBSA3B Subroutine

"egbsa3b"  calculates  the   generalized  Born  polarization 
energy for the  GB/SA and ACE solvation models  for use with 
potential smoothing methods via  analogy to the smoothing of 
Coulomb's law; also partitions the energy among the atoms

EGEOM Subroutine

"egeom"  calculates   the  energy   due  to   restraints  on 
positions,  distances,  angles  and   torsions  as  well  as 
Gaussian basin and spherical droplet restraints

EGEOM1 Subroutine

"egeom1" calculates  the energy  and first  derivatives with 
respect  to  Cartesian  coordinates  due  to  restraints  on 
positions,  distances,  angles  and   torsions  as  well  as 
Gaussian basin and spherical droplet restraints

EGEOM2 Subroutine

"egeom2"  calculates  second  derivatives of  restraints  on 
positions,  distances,  angles  and   torsions  as  well  as 
Gaussian basin and spherical droplet restraints

EGEOM3 Subroutine

"egeom3"  calculates   the  energy  due  to   restraints  on 
positions,  distances,  angles  and   torsions  as  well  as 
Gaussian  basin  and  droplet  restraints;  also  partitions 
energy among the atoms

EHAL Subroutine

"ehal" calculates the buffered 14-7 van der Waals energy

EHAL0A Subroutine

"ehal0a" calculates  the buffered 14-7 van  der Waals energy 
using a pairwise double loop

EHAL0B Subroutine

"ehal0a" calculates  the buffered 14-7 van  der Waals energy 
using the method of lights to locate neighboring atoms

EHAL1 Subroutine

"ehal1" calculates  the buffered  14-7 van der  Waals energy 
and  its   first  derivatives  with  respect   to  Cartesian 
coordinates

EHAL1A Subroutine

"ehal1a" calculates  the buffered 14-7 van  der Waals energy 
and  its   first  derivatives  with  respect   to  Cartesian 
coordinates using a pairwise double loop

EHAL1B Subroutine

"ehal1b" calculates  the buffered 14-7 van  der Waals energy 
and  its   first  derivatives  with  respect   to  Cartesian 
coordinates using the method of lights to locate neighboring 
atoms

EHAL2 Subroutine

"ehal2" calculates  the buffered  14-7 van der  Waals second 
derivatives for a single atom at a time

EHAL3 Subroutine

"ehal3" calculates  the buffered  14-7 van der  Waals energy 
and partitions the energy among the atoms

EHAL3A Subroutine

"ehal3a" calculates  the buffered 14-7 van  der Waals energy 
and partitions the  energy among the atoms  using a pairwise 
double loop

EHAL3B Subroutine

"ehal3b" calculates  the buffered 14-7 van  der Waals energy 
and also  partitions the  energy among  the atoms  using the 
method of lights to locate neighboring atoms

EIGEN Subroutine

"eigen"  uses  the  power  method  to  compute  the  largest 
eigenvalues and  eigenvectors of the metric  matrix, "valid" 
is set true if the first three eigenvalues are positive

EIGENRGD Subroutine

EIGENROT Subroutine

EIGENROT Subroutine

EIGENTOR Subroutine

EIGENXYZ Subroutine

EIMPROP Subroutine

"eimprop" calculates the improper dihedral potential energy

EIMPROP1 Subroutine

"eimprop1" calculates improper dihedral energy and its first 
derivatives with respect to Cartesian coordinates

EIMPROP2 Subroutine

"eimprop2"  calculates second  derivatives  of the  improper 
dihedral angle energy for a single atom

EIMPROP3 Subroutine

"eimprop3"  calculates   the  improper   dihedral  potential 
energy; also partitions the energy terms among the atoms

EIMPTOR Subroutine

"eimptor" calculates the improper torsion potential energy

EIMPTOR1 Subroutine

"eimptor1" calculates improper torsion  energy and its first 
derivatives with respect to Cartesian coordinates

EIMPTOR2 Subroutine

"eimptor2"  calculates second  derivatives  of the  improper 
torsion energy for a single atom

EIMPTOR3 Subroutine

"eimptor3" calculates the improper torsion potential energy; 
also partitions the energy terms among the atoms

ELJ Subroutine

"elj" calculates the Lennard-Jones 6-12 van der Waals energy

ELJ0A Subroutine

"elj0a"  calculates the  Lennard-Jones  6-12  van der  Waals 
energy using a pairwise double loop

ELJ0B Subroutine

"elj0b"  calculates the  Lennard-Jones  6-12  van der  Waals 
energy  using the  method  of lights  to locate  neighboring 
atoms

ELJ1 Subroutine

"elj1"  calculates  the  Lennard-Jones 6-12  van  der  Waals 
energy and  its first derivatives with  respect to Cartesian 
coordinates

ELJ1A Subroutine

"elj1a"  calculates the  Lennard-Jones  6-12  van der  Waals 
energy and  its first derivatives with  respect to Cartesian 
coordinates using a pairwise double loop

ELJ1B Subroutine

"elj1b"  calculates the  Lennard-Jones  6-12  van der  Waals 
energy and  its first derivatives with  respect to Cartesian 
coordinates using the method of lights to locate neighboring 
atoms

ELJ2 Subroutine

"elj2"  calculates  the  Lennard-Jones 6-12  van  der  Waals 
second derivatives for a single atom at a time

ELJ3 Subroutine

"elj3"  calculates  the  Lennard-Jones 6-12  van  der  Waals 
energy and also partitions the energy among the atoms

ELJ3A Subroutine

"elj3a"  calculates the  Lennard-Jones  6-12  van der  Waals 
energy and also partitions the  energy among the atoms using 
a pairwise double loop

ELJ3B Subroutine

"elj3b"  calculates the  Lennard-Jones  6-12  van der  Waals 
energy and also partitions the  energy among the atoms using 
the method of lights to locate neighboring atoms

EMBED Subroutine

"embed" is  a distance geometry routine  patterned after the 
ideas of Gordon Crippen, Irwin Kuntz and Tim Havel; it takes 
as input a  set of upper and lower bounds  on the interpoint 
distances,  chirality restraints  and torsional  restraints, 
and attempts to  generate a set of  coordinates that satisfy 
the input bounds and restraints

EMETAL Subroutine

"emetal" calculates the transition metal ligand field energy

EMETAL1 Subroutine

"emetal1"  calculates  the  transition  metal  ligand  field 
energy and  its first derivatives with  respect to Cartesian 
coordinates

EMETAL2 Subroutine

"emetal2"  calculates  the  transition  metal  ligand  field 
second derivatives for a single atom at a time

EMETAL3 Subroutine

"emetal3"  calculates  the  transition  metal  ligand  field 
energy and also partitions the energy among the atoms

EMM3HB Subroutine

"emm3hb"  calculates  the  MM3   exp-6  van  der  Waals  and 
directional charge transfer hydrogen bonding energy

EMM3HB0A Subroutine

"emm3hb0a"  calculates  the  MM3  exp-6 van  der  Waals  and 
directional charge transfer hydrogen  bonding energy using a 
pairwise double loop

EMM3HB0B Subroutine

"emm3hb0b"  calculates  the  MM3  exp-6 van  der  Waals  and 
directional  charge transfer  hydrogen bonding  energy using 
the method of lights to locate neighboring atoms

EMM3HB1 Subroutine

"emm3hb1"  calculates  the  MM3  exp-6  van  der  Waals  and 
directional  charge transfer  hydrogen  bonding energy  with 
respect to Cartesian coordinates

EMM3HB1A Subroutine

"emm3hb1a"  calculates  the  MM3  exp-6 van  der  Waals  and 
directional  charge transfer  hydrogen  bonding energy  with 
respect  to Cartesian  coordinates using  a pairwise  double 
loop

EMM3HB1B Subroutine

"emm3hb1b"  calculates  the  MM3  exp-6 van  der  Waals  and 
directional  charge transfer  hydrogen  bonding energy  with 
respect to Cartesian coordinates  using the method of lights 
to locate neighboring atoms

EMM3HB2 Subroutine

"emm3hb2"  calculates  the  MM3  exp-6  van  der  Waals  and 
directional   charge   transfer  hydrogen   bonding   second 
derivatives for a single atom at a time

EMM3HB3 Subroutine

"emm3hb3"  calculates  the  MM3  exp-6  van  der  Waals  and 
directional  charge transfer  hydrogen  bonding energy,  and 
partitions the energy among the atoms

EMM3HB3A Subroutine

"emm3hb3"  calculates  the  MM3  exp-6  van  der  Waals  and 
directional  charge transfer  hydrogen  bonding energy,  and 
partitions the energy among the atoms

EMM3HB3B Subroutine

"emm3hb3b"  calculates  the  MM3  exp-6 van  der  Waals  and 
directional  charge transfer  hydrogen bonding  energy using 
the method of lights to locate neighboring atoms

EMPOLE Subroutine

"empole" calculates  the electrostatic energy due  to atomic 
multipole interactions and dipole polarizability

EMPOLE0A Subroutine

"empole0a" calculates the electrostatic energy due to atomic 
multipole  interactions and  dipole  polarizability using  a 
pairwise double loop

EMPOLE0B Subroutine

"empole0b" calculates the electrostatic energy due to atomic 
multipole  interactions and  dipole  polarizability using  a 
regular Ewald summation

EMPOLE1 Subroutine

"empole1" calculates  the multipole and  dipole polarization 
energy and derivatives with respect to Cartesian coordinates

EMPOLE1A Subroutine

"empole1a" calculates the  multipole and dipole polarization 
energy and derivatives with respect to Cartesian coordinates 
using a pairwise double loop

EMPOLE1B Subroutine

"empole1b" calculates the  multipole and dipole polarization 
energy and derivatives with respect to Cartesian coordinates 
using a regular Ewald summation

EMPOLE2 Subroutine

"empole2" calculates second derivatives of the multipole and 
dipole polarization energy for a single atom at a time

EMPOLE2A Subroutine

"empole2a" computes multipole  and dipole polarization first 
derivatives  for a  single  atom with  respect to  Cartesian 
coordinates;   used   to   get  finite   difference   second 
derivatives

EMPOLE3 Subroutine

"empole3" calculates the electrostatic  energy due to atomic 
multipole  interactions   and  dipole   polarizability,  and 
partitions the energy among the atoms

EMPOLE3A Subroutine

"empole3a" calculates the electrostatic energy due to atomic 
multipole  interactions   and  dipole   polarizability,  and 
partitions the energy among the atoms using a double loop

EMPOLE3B Subroutine

"empole3b" calculates the electrostatic energy due to atomic 
multipole  interactions   and  dipole   polarizability,  and 
partitions the energy among the  atoms using a regular Ewald 
summation

ENERGY Function

"energy" calls  the subroutines  to calculate  the potential 
energy terms and sums up to form the total energy

ENRGYZE Subroutine

"energyze" is  an auxiliary routine for  the analyze program 
that performs the  energy analysis and prints  the total and 
intermolecular energies

EOPBEND Subroutine

"eopbend" computes the out-of-plane bend potential energy at 
trigonal centers via a Wilson-Decius-Cross angle bend

EOPBEND1 Subroutine

"eopbend1" computes  the out-of-plane bend  potential energy 
and  first derivatives  at  trigonal centers  via a  Wilson-
Decius-Cross angle bend

EOPBEND2 Subroutine

"eopbend2" calculates second derivatives of the out-of-plane 
bend  energy  via a  Wilson-Decius-Cross  angle  bend for  a 
single atom using finite difference methods

EOPBEND2A Subroutine

"eopbend2a"    calculates    out-of-plane   bending    first 
derivatives at  a trigonal center via  a Wilson-Decius-Cross 
angle bend; used in  computation of finite difference second 
derivatives

EOPBEND3 Subroutine

"eopbend3" computes  the out-of-plane bend  potential energy 
at trigonal  centers via  a Wilson-Decius-Cross  angle bend; 
also partitions the energy among the atoms

EOPDIST Subroutine

"eopdist"  computes  the   out-of-plane  distance  potential 
energy at trigonal centers via the central atom height

EOPDIST1 Subroutine

"eopdist1"  computes  the  out-of-plane  distance  potential 
energy  and first  derivatives at  trigonal centers  via the 
central atom height

EOPDIST2 Subroutine

"eopdist2" calculates second derivatives of the out-of-plane 
distance  energy for  a  single atom  via  the central  atom 
height

EOPDIST3 Subroutine

"eopdist3"  computes  the  out-of-plane  distance  potential 
energy at trigonal centers via the central atom height; also 
partitions the energy among the atoms

EPME Subroutine

"epme" computes  the reciprocal space energy  for a particle 
mesh Ewald summation over partial charges

EPME1 Subroutine

"epme1"  computes  the  reciprocal space  energy  and  first 
derivatives for a particle mesh Ewald summation

EPME3 Subroutine

"epme3" computes the reciprocal  space energy for a particle 
mesh  Ewald  summation  over   partial  charges  and  prints 
information about the energy over the charge grid points

EPUCLC Subroutine

EREAL Subroutine

"ereal"  evaluates the  real  space portion  of the  regular 
Ewald summation energy due  to atomic multipole interactions 
and dipole polarizability

EREAL1 Subroutine

"ereal1"  evaluates the  real space  portion of  the regular 
Ewald summation energy and  gradient due to atomic multipole 
interactions and dipole polarizability

EREAL3 Subroutine

"ereal3"  evaluates the  real space  portion of  the regular 
Ewald summation energy due  to atomic multipole interactions 
and dipole  polarizability and  partitions the  energy among 
the atoms

ERECIP Subroutine

"erecip"  evaluates  the  reciprocal space  portion  of  the 
regular  Ewald  summation  energy due  to  atomic  multipole 
interactions and dipole polarizability

ERECIP1 Subroutine

"erecip1"  evaluates the  reciprocal  space  portion of  the 
regular Ewald  summation energy  and gradient due  to atomic 
multipole interactions and dipole polarizability

ERECIP3 Subroutine

"erecip3"  evaluates the  reciprocal  space  portion of  the 
regular  Ewald  summation  energy due  to  atomic  multipole 
interactions   and   dipole   polarizability,   and   prints 
information  about the  energy over  the reciprocal  lattice 
vectors

ERF Function

"erf" computes a numerical approximation to the value of the 
error function via a Chebyshev approximation

ERFC Function

"erfc" computes  a numerical  approximation to the  value of 
the   complementary   error   function   via   a   Chebyshev 
approximation

ERFCORE Subroutine

"erfcore" evaluates erf(x) or erfc(x) for a real argument x; 
when called with  mode set to 0 it returns erf,  a mode of 1 
returns  erfc;  uses  rational  functions  that  approximate 
erf(x) and erfc(x) to at least 18 significant decimal digits

ERFIK Subroutine

ERFINV Function

"erfinv" evaluates the inverse of the error function erf for 
a  real  argument  in  the range  (-1,1)  using  a  rational 
function approximation followed  by cycles of Newton-Raphson 
correction

ERXNFLD Subroutine

"erxnfld" calculates the macroscopic reaction field energy

ERXNFLD1 Subroutine

"erxnfld1" calculates the  macroscopic reaction field energy 
and derivatives with respect to Cartesian coordinates

ERXNFLD2 Subroutine

"erxnfld2" calculates second  derivatives of the macroscopic 
reaction field energy for a single atom at a time

ERXNFLD3 Subroutine

"erxnfld3" calculates the macroscopic reaction field energy, 
and also partitions the energy among the atoms

ESOLV Subroutine

"esolv" calculates the continuum solvation energy via either 
the Eisenberg-McLachlan ASP  model, Ooi-Scheraga SASA model, 
various GB/SA methods or the ACE model

ESOLV1 Subroutine

"esolv1" calculates the continuum solvation energy and first 
derivatives  with  respect  to Cartesian  coordinates  using 
either  the Eisenberg-McLachlan  ASP,  Ooi-Scheraga SASA  or 
various GB/SA solvation models

ESOLV2 Subroutine

"esolv2"  calculates  second  derivatives of  the  continuum 
solvation energy  using either the  Eisenberg-McLachlan ASP, 
Ooi-Scheraga SASA or various GB/SA solvation models

ESOLV3 Subroutine

"esolv3"  calculates the  continuum  solvation energy  using 
either the Eisenberg-McLachlan  ASP model, Ooi-Scheraga SASA 
model,  various  GB/SA  methods   or  the  ACE  model;  also 
partitions the energy among the atoms

ESTRBND Subroutine

"estrbnd" calculates the stretch-bend potential energy

ESTRBND1 Subroutine

"estrbnd1" calculates the  stretch-bend potential energy and 
first derivatives with respect to Cartesian coordinates

ESTRBND2 Subroutine

"estrbnd2"  calculates  the  stretch-bend  potential  energy 
second derivatives with respect to Cartesian coordinates

ESTRBND3 Subroutine

"estrbnd3"  calculates  the stretch-bend  potential  energy; 
also partitions the energy among the atoms

ESTRTOR Subroutine

"estrtor" calculates the stretch-torsion potential energy

ESTRTOR1 Subroutine

"estrtor1" calculates  the stretch-torsion energy  and first 
derivatives with respect to Cartesian coordinates

ESTRTOR2 Subroutine

"estrtor2" calculates  the stretch-torsion  potential energy 
second derivatives with respect to Cartesian coordinates

ESTRTOR3 Subroutine

"estrtor3" calculates the  stretch-torsion potential energy; 
also partitions the energy terms among the atoms

ETORS Subroutine

"etors" calculates the torsional potential energy

ETORS1 Subroutine

"etors1"  calculates torsional  potential  energy and  first 
derivatives with respect to Cartesian coordinates

ETORS2 Subroutine

"etors2"  calculates  second  derivatives of  the  torsional 
energy for a single atom

ETORS3 Subroutine

"etors3"  calculates the  torsional  potential energy;  also 
partitions the energy terms among the atoms

EUREY Subroutine

"eurey" calculates the Urey-Bradley 1-3 interaction energy

EUREY1 Subroutine

"eurey1" calculates the  Urey-Bradley interaction energy and 
its first derivatives with respect to Cartesian coordinates

EUREY2 Subroutine

"eurey2" calculates  second derivatives of  the Urey-Bradley 
interaction energy for a single atom at a time

EUREY3 Subroutine

"eurey3" calculates the Urey-Bradley energy; also partitions 
the energy among the atoms

EWALDCOF Subroutine

"ewaldcof" finds a value of  the Ewald coefficient such that 
all terms beyond the specified  cutoff distance will have an 
value less than a specified tolerance

EXPLORE Subroutine

"explore"  uses  simulated  annealing on  an  initial  crude 
embedded distance  geoemtry structure  to refine  versus the 
bound, chirality, planarity and torsional error functions

EXTRA Subroutine

"extra"  calculates any  additional  user defined  potential 
energy contribution

EXTRA1 Subroutine

"extra1"  calculates any  additional user  defined potential 
energy contribution and its first derivatives

EXTRA2 Subroutine

"extra2"  calculates second  derivatives  of any  additional 
user defined potential energy contribution for a single atom 
at a time

EXTRA3 Subroutine

"extra3"  calculates any  additional user  defined potential 
contribution and also partitions the energy among the atoms

FATAL Subroutine

"fatal" terminates execution due to a user request, a severe 
error or some other nonstandard condition

FFTBACK Subroutine

FFTFRONT Subroutine

FFTSETUP Subroutine

FIELD Subroutine

"field" sets the force field potential energy functions from 
a parameter file and modifications specified in a keyfile

FINAL Subroutine

"final" performs any final  program actions, prints a status 
message, and then  pauses if necessary to  avoid closing the 
execution window

FINDATM Subroutine

"findatm" locates  a specific  PDB atom  name type  within a 
range of atoms  from the PDB file, returns zero  if the name 
type was not found

FIXPDB Subroutine

"fixpdb"  corrects problems  with  PDB  files by  converting 
residue and atom names to the forms used by TINKER

FRACDIST Subroutine

"fracdist"  computes   a  normalized  distribution   of  the 
pairwise fractional distances between the smoothed upper and 
lower bounds

FREEUNIT Function

"freeunit" finds  an unopened  Fortran I/O unit  and returns 
its numerical value from 1 to 99; the units already assigned 
to "input"  and "iout" (usually  5 and 6) are  skipped since 
they have special meaning as the default I/O units

GAMMLN Function

"gammln" uses a  series expansion due to  Lanczos to compute 
the natural logarithm of the Gamma function at "x" in [0,1]

GDA Program

"gda" implements Gaussian  Density Annealing (GDA) algorithm 
for global optimization via simulated annealing

GDA1 Function

GDA2 Function

GDA3 Subroutine

GDASTAT Subroutine

GENDOT Subroutine

"gendot"  finds the  coordinates  of a  specified number  of 
surface  points  for a  sphere  with  the input  radius  and 
coordinate center

GEODESIC Subroutine

"geodesic" smooths  the upper and lower  distance bounds via 
the triangle inequality  using a sparse matrix  version of a 
shortest path algorithm

GEOMETRY Function

"geometry"  finds the  value  of  the interatomic  distance, 
angle or dihedral angle defined by two to four input atoms

GETBASE Subroutine

"getbase" finds the base heavy atoms for a single nucleotide 
residue and copies the names  and coordinates to the Protein 
Data Bank file

GETIME Subroutine

"getime" gets elapsed CPU time in seconds for an interval

GETINT Subroutine

"getint"  asks for  an internal  coordinate file  name, then 
reads  the  internal   coordinates  and  computes  Cartesian 
coordinates

GETKEY Subroutine

"getkey" finds  a valid keyfile  and stores its  contents as 
line images for subsequent keyword parameter searching

GETMOL2 Subroutine

"getmol2" asks  for a  Sybyl MOL2  molecule file  name, then 
reads the coordinates from the file

GETNUCH Subroutine

"getnuch" finds  the nucleotide hydrogen atoms  for a single 
residue and copies the names  and coordinates to the Protein 
Data Bank file

GETNUMB Subroutine

"getnumb" searchs an input string  from left to right for an 
integer and puts the numeric value in "number"; returns zero 
with "next" unchanged if no integer value is found

GETPDB Subroutine

"getpdb" asks for a Protein  Data Bank file name, then reads 
in the coordinates file

GETPRB Subroutine

"getprb"  tests  for  a   possible  probe  position  at  the 
interface between three neighboring atoms

GETPRM Subroutine

"getprm" finds the potential  energy parameter file and then 
opens and reads the parameters

GETPROH Subroutine

"getproh" finds the  hydrogen atoms for a  single amino acid 
residue and copies the names  and coordinates to the Protein 
Data Bank file

GETREF Subroutine

"getref"  copies structure  information  from the  reference 
area  into the  standard  variables for  the current  system 
structure

GETSEQ Subroutine

"getseq"  asks the  user  for the  amino  acid sequence  and 
torsional angle values needed to define a peptide

GETSEQN Subroutine

"getseqn"  asks the  user  for the  nucleotide sequence  and 
torsional angle values needed to define a nucleic acid

GETSIDE Subroutine

"getside"  finds the  side chain  heavy atoms  for a  single 
amino acid residue  and copies the names  and coordinates to 
the Protein Data Bank file

GETSTRING Subroutine

"getstring" searchs for a quoted text string within an input 
character string;  the region  between the first  and second 
quotes is returned as the "text";  if the actual text is too 
long, only the first part is returned

GETTEXT Subroutine

"gettext" searchs  an input string  for the first  string of 
non-blank characters; the region  from a non-blank character 
to  the first  blank space  is  returned as  "text"; if  the 
actual text is too long, only the first part is returned

GETTOR Subroutine

"gettor"  tests  for  a   possible  torus  position  at  the 
interface  between two  atoms, and  finds the  torus radius, 
center and axis

GETWORD Subroutine

"getword" searchs  an input string for  the first alphabetic 
character (A-Z or a-z); the region from this first character 
to the first  blank space or comma is returned  as a "word"; 
if  the actual  word is  too long,  only the  first part  is 
returned

GETXYZ Subroutine

"getxyz"  asks for  a Cartesian  coordinate file  name, then 
reads in the coordinates file

GRADIENT Subroutine

"gradient"  calls  subroutines  to calculate  the  potential 
energy  and  first  derivatives with  respect  to  Cartesian 
coordinates

GRADRGD Subroutine

"gradrgd"  calls  subroutines  to  calculate  the  potential 
energy  and first  derivatives  with respect  to rigid  body 
coordinates

GRADROT Subroutine

"gradrot"  calls  subroutines  to  calculate  the  potential 
energy and its torsional first derivatives

GRAFIC Subroutine

"grafic" outputs the upper & lower triangles and diagonal of 
a square matrix in a schematic form for visual inspection

GROUPS Subroutine

"groups" tests a set of atoms to see if all are members of a 
single atom group or a pair  of atom groups; if so, then the 
correct intra- or intergroup weight is assigned

GRPLINE Subroutine

"grpline" tests each  atom group for linearity  of the sites 
contained in the group

GYRATE Subroutine

"gyrate"  computes the  radius  of gyration  of a  molecular 
system from its atomic coordinates

HANGLE Subroutine

"hangle" constructs hybrid angle bending parameters given an 
initial state, final state and "lambda" value

HATOM Subroutine

"hatom" assigns a new atom type to each hybrid site

HBOND Subroutine

"hbond" constructs  hybrid bond stretch parameters  given an 
initial state, final state and "lambda" value

HCHARGE Subroutine

"hcharge"  constructs hybrid  charge interaction  parameters 
given an initial state, final state and "lambda" value

HDIPOLE Subroutine

"hdipole"  constructs hybrid  dipole interaction  parameters 
given an initial state, final state and "lambda" value

HESSIAN Subroutine

"hessian"  calls   subroutines  to  calculate   the  Hessian 
elements for  each atom  in turn  with respect  to Cartesian 
coordinates

HESSRGD Subroutine

"hessrgd"  computes  the  numerical  Hessian  elements  with 
respect to rigid body coordinates; either the full matrix or 
just the diagonal  can be calculated; the  full matrix needs 
6*ngroup+1 gradient evaluations  while the diagonal requires 
just two gradient calls

HESSROT Subroutine

"hessrot"  computes  the  numerical  Hessian  elements  with 
respect to torsional angles; either  the full matrix or just 
the  diagonal  can  be  calculated; the  full  matrix  needs 
nomega+1  gradient evaluations  while the  diagonal requires 
just two gradient calls

HIMPTOR Subroutine

"himptor"  constructs hybrid  improper torsional  parameters 
given an initial state, final state and "lambda" value

HSTRBND Subroutine

"hstrbnd" constructs hybrid stretch-bend parameters given an 
initial state, final state and "lambda" value

HSTRTOR Subroutine

"hstrtor" constructs hybrid stretch-torsion parameters given 
an initial state, final state and "lambda" value

HTORS Subroutine

"htors" constructs  hybrid torsional parameters for  a given 
initial state, final state and "lambda" value

HVDW Subroutine

"hvdw" constructs hybrid van  der Waals  parameters given an 
initial state, final state and "lambda" value

HYBRID Subroutine

"hybrid" constructs  the hybrid hamiltonian for  a specified 
initial state, final state and mutation parameter "lambda"

IJK_PT Subroutine

IMAGE Subroutine

"image" takes  the components  of pairwise  distance between 
two points  in the  same or  neighboring periodic  boxes and 
converts to the components of the minimum image distance

IMPOSE Subroutine

"impose" performs  the least  squares best  superposition of 
two  atomic coordinate  sets via  a quaternion  method; upon 
return,  the first  coordinate  set is  unchanged while  the 
second set is  translated and rotated to give  best fit; the 
final root mean square fit is returned in "rmsvalue"

INDUCE Subroutine

"induce"  computes   the  induced  dipole  moment   at  each 
polarizable site due to direct or mutual polarization

INDUCE0A Subroutine

"induce0a"  computes  the  induced  dipole  moment  at  each 
polarizable site using a pairwise double loop

INDUCE0B Subroutine

"induce0b"  computes  the  induced  dipole  moment  at  each 
polarizable site using a regular Ewald summation

INEDGE Subroutine

"inedge" inserts a concave edge into the linked list for its 
temporary torus

INERTIA Subroutine

"inertia" computes the principal  moments of inertia for the 
system, and optionally translates the  center of mass to the 
origin and rotates the principal axes onto the global axes

INITERR Function

"initerr" is the initial  error function and derivatives for 
a distance  geometry embedding; it includes  components from 
the local geometry and torsional restraint errors

INITIAL Subroutine

"initial" sets  up original  values for some  parameters and 
variables that might not otherwise get initialized

INITPRM Subroutine

"initprm" completely  initializes a  force field  by setting 
all parameters to zero and using defaults for control values

INITRES Subroutine

"initres" sets  names for  biopolymer residue types  used in 
PDB file conversion and automated generation of structures

INITROT Subroutine

"initrot" asks for torsional angles  which are to be rotated 
in subsequent computation, it  will automatically locate all 
rotatable  single   bonds  if   desired;  assumes   that  an 
appropriate internal coordinates file  has already been read 
in

INSERT Subroutine

"insert"   adds  the   specified  atom   to  the   Cartesian 
coordinates list and shifts the remaining atoms

INTEDIT Program

"intedit"  allows the  user to  extract information  from or 
alter the values within an internal coordinates file

INTXYZ Program

"intxyz"  takes  as  input  an  internal  coordinates  file, 
converts to and then writes out Cartesian coordinates

INVBETA Function

"invbeta"  computes the  inverse Beta  distribution function 
via a combination of Newton iteration and bisection search

INVERT Subroutine

"invert" inverts a matrix using the Gauss-Jordan method

IPEDGE Subroutine

"ipedge" inserts convex edge into linked list for atom

JACOBI Subroutine

"jacobi"  performs  a  matrix   diagonalization  of  a  real 
symmetric matrix by the method of Jacobi rotations

KANGANG Subroutine

"kangang" assigns the parameters  for angle-angle cross term 
interactions and processes new or changed parameter values

KANGLE Subroutine

"kangle" assigns  the force  constants and ideal  angles for 
the bond angles; also processes new or changed parameters

KATOM Subroutine

"katom" assigns an atom type definitions to each atom in the 
structure and processes any new or changed values

KBOND Subroutine

"kbond" assigns  a force constant  and ideal bond  length to 
each bond in the structure  and processes any new or changed 
parameter values

KCHARGE Subroutine

"kcharge" assigns  partial charges  to the atoms  within the 
structure and processes any new or changed values

KCHIRAL Subroutine

"kchiral" determines the target value for each chirality and 
planarity   restraint   as   the  signed   volume   of   the 
parallelpiped spanned by vectors from  a common atom to each 
of three other atoms

KDIPOLE Subroutine

"kdipole"  assigns  bond dipoles  to  the  bonds within  the 
structure and processes any new or changed values

KENEG Subroutine

"keneg" applies primary and secondary electronegativity bond 
length corrections to applicable bond parameters

KEWALD Subroutine

"kewald" assigns  both regular Ewald summation  and particle 
mesh Ewald parameters for a periodic box

KGEOM Subroutine

"kgeom" asisgns parameters for  geometric restraint terms to 
be included in the potential energy calculation

KIMPROP Subroutine

"kimprop"  assigns  potential  parameters to  each  improper 
dihedral in the structure and processes any changed values

KIMPTOR Subroutine

"kimptor"  assigns  torsional  parameters to  each  improper 
torsion in the structure and processes any changed values

KMETAL Subroutine

"kmetal" assigns ligand field parameters to transition metal 
atoms and processes any new or changed parameter values

KMPOLE Subroutine

"kmpole" assigns  atomic multipole  moments to the  atoms of 
the structure and processes any new or changed values

KOPBEND Subroutine

"kopbend"  assigns  the  force  constants  for  out-of-plane 
bending  at trigonal  centers via  Wilson-Decius-Cross angle 
bends; also processes any new or changed parameter values

KOPDIST Subroutine

"kopdist"  assigns  the  force  constants  for  out-of-plane 
distance at  trigonal centers  via the central  atom height; 
also processes any new or changed parameter values

KORBIT Subroutine

"korbit" assigns pi-orbital parameters to conjugated systems 
and processes any new or changed parameters

KPOLAR Subroutine

"kpolar" assigns atomic dipole polarizabilities to the atoms 
within the structure and processes any new or changed values

KSOLV Subroutine

"ksolv"  assigns continuum  solvation energy  parameters for 
the  Eisenberg-McLachlan ASP,  Ooi-Scheraga SASA  or various 
GB/SA solvation models

KSTRBND Subroutine

"kstrbnd"  assigns  the   parameters  for  the  stretch-bend 
interactions and processes new or changed parameter values

KSTRTOR Subroutine

"kstrtor"  assigns  stretch-torsion parameters  to  torsions 
needing them, and processes any new or changed values

KTORS Subroutine

"ktors" assigns torsional parameters  to each torsion in the 
structure and processes any new or changed values

KUREY Subroutine

"kurey" assigns the force  constants and ideal distances for 
the Urey-Bradley 1-3 interactions; also processes any new or 
changed parameter values

KVDW Subroutine

"kvdw" assigns  the parameters to  be used in  computing the 
van der Waals interactions and  processes any new or changed 
values for these parameters

LATTICE Subroutine

"lattice" stores the periodic  box dimensions and sets angle 
values to be used in computing fractional coordinates

LBFGS Subroutine

"lbfgs"  is a  limited  memory  BFGS quasi-newton  nonlinear 
optimization routine

LIGASE Subroutine

"ligase" translates a nucleic acid structure in Protein Data 
Bank format to a Cartesian coordinate file and sequence file

LIGHTS Subroutine

"lights" computes  the set of nearest  neighbor interactions 
using the method of lights algorithm

LINBODY Subroutine

"linbody" finds the angular velocity of a linear rigid body

LMSTEP Subroutine

"lmstep"  computes  the  Levenberg-Marquardt step  during  a 
nonlinear least  squares calculation; this version  is based 
upon ideas from the Minpack routine LMPAR together with with 
the internal doubling strategy of Dennis and Schnabel

LOCALMIN Subroutine

"localmin"  is  used  during  normal mode  local  search  to 
perform a Cartesian coordinate energy minimization

LOCALRGD Subroutine

"localrgd" is used during the  PSS local search procedure to 
perform a rigid body energy minimization

LOCALROT Subroutine

"localrot" is used during the  PSS local search procedure to 
perform a torsional space energy minimization

LOCALXYZ Subroutine

"localxyz" is used during the potential smoothing and search 
procedure  to perform  a local  optimization at  the current 
smoothing level

LOCERR Function

"locerr"   is  the   local  geometry   error  function   and 
derivatives including  the 1-2,  1-3 and 1-4  distance bound 
restraints

LOWCASE Subroutine

"lowcase" converts a text string to all lower case letters

MAJORIZE Subroutine

"majorize" refines  the projected coordinates  by attempting 
to  minimize the  least  square residual  between the  trial 
distance  matrix   and  the  distances  computed   from  the 
coordinates

MAKEINT Subroutine

"makeint" converts  Cartesian to internal  coordinates where 
selection of internal coordinates is controlled by "mode"

MAKEPDB Subroutine

"makexyz" converts a set of Cartesian coordinates to Protein 
Data  Bank   format  with   special  handling   for  systems 
consisting   of  polypeptide   chains,  ligands   and  water 
molecules

MAKEREF Subroutine

"makeref" copies the information contained in the "xyz" file 
of the current structure into corresponding reference areas

MAKEXYZ Subroutine

"makexyz" generates a complete  set of Cartesian coordinates 
for a full structure from the internal coordinate values

MAPCHECK Subroutine

"mapcheck" checks  the current minimum energy  structure for 
possible addition to the master list of local minima

MAXWELL Function

"maxwell" returns  a speed in  Angstroms/picosecond randomly 
selected from  a 3-D Maxwell-Boltzmann distribution  for the 
specified particle mass and system temperature

MDINIT Subroutine

"mdinit" initializes the velocities  and accelerations for a 
molecular dynamics trajectory, including restarts

MDREST Subroutine

"mdrest" finds  and removes any translational  or rotational 
kinetic energy of the overall system center of mass

MDSAVE Subroutine

"mdsave" writes molecular  dynamics trajectory snapshots and 
auxiliary   files   with   velocity   and   induced   dipole 
information; also checks for user requested termination of a 
simulation

MDSTAT Subroutine

"mdstat" is called  at each molecular dynamics  time step to 
form statistics on various  average values and fluctuations, 
and to periodically save the state of the trajectory

MEASFN Subroutine

MEASFP Subroutine

MEASFS Subroutine

MEASPM Subroutine

"measpm" computes  the volume of  a single prism  section of 
the full interior polyhedron

MECHANIC Subroutine

"mechanic"  sets  up  needed parameters  for  the  potential 
energy calculation and reads in  many of the user selectable 
options

MERGE Subroutine

"merge" combines the reference and current structures into a 
single  new  "current"  structure containing  the  reference 
atoms followed by the atoms of the current structure

METRIC Subroutine

"metric"  takes  as  input  the trial  distance  matrix  and 
computes  the metric  matrix  of all  possible dot  products 
between the atomic vectors and  the center of mass using the 
law of cosines  and the following formula  for the distances 
to the center of mass:

MIDERR Function

"miderr" is the secondary error function and derivatives for 
a distance  geometry embedding; it includes  components from 
the distance bounds, local geometry, chirality and torsional 
restraint errors

MINIMIZ1 Function

"minimiz1" is a service routine that computes the energy and 
gradient for  a low  storage BFGS optimization  in Cartesian 
coordinate space

MINIMIZE Program

"minimize"   performs  energy   minimization  in   Cartesian 
coordinate  space   using  a  low  storage   BFGS  nonlinear 
optimization

MINIROT Program

"minirot" performs an energy minimization in torsional angle 
space using a low storage BFGS nonlinear optimization

MINIROT1 Function

"minirot1" is a service routine that computes the energy and 
gradient for  a low  storage BFGS nonlinear  optimization in 
torsional angle space

MINPATH Subroutine

"minpath"  is a  routine for  finding the  triangle smoothed 
upper and lower bounds of each atom to a specified root atom 
using  a sparse  variant of  the Bellman-Ford  shortest path 
algorithm

MINRIGID Program

"minrigid"  performs an  energy minimization  of rigid  body 
atom groups using a low storage BFGS nonlinear optimization

MINRIGID1 Function

"minrigid1" is  a service  routine that computes  the energy 
and gradient  for a low storage  BFGS nonlinear optimization 
of rigid bodies

MMID Subroutine

"mmid" implements a modified  midpoint method to advance the 
integration of a set of first order differential equations

MODECART Subroutine

MODEROT Subroutine

MODESRCH Subroutine

MODETORS Subroutine

MODULI Subroutine

"moduli"  sets the  moduli of  the inverse  discrete Fourier 
transform of  the B-splines;  bsmod[1-3] hold  these values, 
nfft[1-3] are the  grid dimensions, bsorder is  the order of 
B-spline approximation

MOLECULE Subroutine

"molecule" counts  the molecules,  assigns each atom  to its 
molecule and computes the mass of each molecule

MOLUIND Subroutine

"moluind" computes  the molecular induced  dipole components 
in the presence of an external electric field

MOMENTS Subroutine

"moments"  computes the  total electric  charge, dipole  and 
quadrupole moments for  the entire system as a  sum over the 
partial charges, bond dipoles and atomic multipole moments

MUTATE Subroutine

"mutate" constructs  the hybrid hamiltonian for  a specified 
initial state, final state and mutation parameter "lambda"

NEIGHBOR Subroutine

"neighbor" finds all of the neighbors of each atom

NEWATM Subroutine

"newatm"  creates  and  defines   an  atom  needed  for  the 
Cartesian coordinates file, but which may not present in the 
original Protein Data Bank file

NEWCRD Subroutine

"newcrd"  computes updated  atomic coordinates  for a  rigid 
body given the previous coordinates, the rotation matrix and 
shift in the center of mass corresponding to the motion

NEWTON Program

"newton"  performs  an   energy  minimization  in  Cartesian 
coordinate space using a truncated Newton method

NEWTON1 Function

"newton1" is a service routine  that computes the energy and 
gradient  for  truncated  Newton optimization  in  Cartesian 
coordinate space

NEWTON2 Subroutine

"newton2"  is a  service  routine that  computes the  sparse 
matrix Hessian elements for truncated Newton optimization in 
Cartesian coordinate space

NEWTROT Program

"newtrot" performs an energy minimization in torsional angle 
space using a truncated Newton conjugate gradient method

NEWTROT1 Function

"newtrot1" is a service routine that computes the energy and 
gradient   for    truncated   Newton    conjugate   gradient 
optimization in torsional angle space

NEWTROT2 Subroutine

"newtrot2"  is a  service routine  that computes  the sparse 
matrix Hessian elements for truncated Newton optimization in 
torsional angle space

NEXTARG Subroutine

"nextarg" finds  the next  unused command line  argument and 
returns it in the input character string

NEXTTEXT Function

"nexttext" finds and returns the  location of the first non-
blank  character  within  an  input  text  string;  zero  is 
returned if no such character is found

NORMAL Function

"normal" generates  a random  number from a  normal Gaussian 
distribution with a mean of zero and a variance of one

NUCBASE Subroutine

"nucbase" builds the side chain for a single nucleotide base 
in terms of internal coordinates

NUCCHAIN Subroutine

"nucchain" builds up the  internal coordinates for a nucleic 
acid sequence  from the sugar type,  backbone and glycosidic 
torsional values

NUCLEIC Program

"nucleic" builds the internal and Cartesian coordinates of a 
polynucleotide  from  nucleic  acid sequence  and  torsional 
angle values for the nucleic acid backbone and side chains

NUMBER Function

"number" converts a text numeral  into an integer value; the 
input string must contain only numeric characters

NUMERAL Subroutine

"numeral"  converts   an  input  integer  number   into  the 
corresponding right- or left-justified text numeral

NUMGRAD Subroutine

"numgrad" computes  the gradient  of the  objective function 
"fvalue" with respect to  Cartesian coordinates of the atoms 
via a two-sided numerical differentiation

OCVM Subroutine

"ocvm" is an optimally conditioned variable metric nonlinear 
optimization routine without line searches

OLDATM Subroutine

"oldatm" get the Cartesian coordinates  for an atom from the 
Protein  Data Bank  file,  then assigns  the  atom type  and 
atomic connectivities

OPENEND Subroutine

"openend"  opens a  file on  a  Fortran unit  such that  the 
position is  set to the bottom  for appending to the  end of 
the file

OPTIMIZ1 Function

"optimiz1" is a service routine that computes the energy and 
gradient   for   optimally   conditioned   variable   metric 
optimization in Cartesian coordinate space

OPTIMIZE Program

"optimize"   performs  energy   minimization  in   Cartesian 
coordinate  space using  an  optimally conditioned  variable 
metric method

OPTIROT Program

"optirot" performs an energy minimization in torsional angle 
space using an optimally conditioned variable metric method

OPTIROT1 Function

"optirot1" is a service routine that computes the energy and 
gradient   for   optimally   conditioned   variable   metric 
optimization in torsional angle space

OPTRIGID Program

"optrigid"  performs an  energy minimization  of rigid  body 
atom groups  using an optimally conditioned  variable metric 
method

OPTRIGID1 Function

"optrigid1" is  a service  routine that computes  the energy 
and  gradient  for  optimally  conditioned  variable  metric 
optimization of rigid bodies

ORBITAL Subroutine

"orbital" finds and organizes lists  of atoms in a pisystem, 
bonds  connecting  pisystem  atoms and  torsions  whose  two 
central atoms are both pisystem atoms

ORIENT Subroutine

"orient" computes  a set of reference  Cartesian coordinates 
in standard orientation for each rigid body atom group

ORTHOG Subroutine

"orthog" performs  an orthogonalization  of an  input matrix 
via the modified Gram-Schmidt algorithm

OVERLAP Subroutine

"overlap" computes  the overlap for two  parallel p-orbitals 
given the atomic numbers and distance of separation

PARAMYZE Subroutine

"paramyze"  prints the  force field  parameters used  in the 
computation of each of the potential energy terms

PASSB Subroutine

PASSB2 Subroutine

PASSB3 Subroutine

PASSB4 Subroutine

PASSB5 Subroutine

PASSF Subroutine

PASSF2 Subroutine

PASSF3 Subroutine

PASSF4 Subroutine

PASSF5 Subroutine

PATH Program

"path" locates a series of structures equally spaced along a 
conformational  pathway connecting  the  input reactant  and 
product  structures; a  series of  constrained optimizations 
orthogonal to the path is done via Lagrangian multipliers

PATH1 Function

PATHPNT Subroutine

"pathpnt" finds a structure  on the synchronous transit path 
with the specified path value "t"

PATHSCAN Subroutine

"pathscan" makes a scan of  a synchronous transit pathway by 
computing structures and energies for specific path values

PATHVAL Subroutine

"pathval" computes  the synchronous  transit path  value for 
the specified structure

PDBATM Subroutine

"pdbatm" adds an atom to the Protein Data Bank file

PDBXYZ Program

"pdbxyz" takes  as input a  Protein Data Bank file  and then 
converts to and writes out a Cartesian coordinates file and, 
for polypeptides, a sequence file

PIALTER Subroutine

"pialter" first  modifies bond  lengths and  force constants 
according to the standard bond slope parameters and the bond 
order  values  stored in  "pnpl";  also  alters some  2-fold 
torsional parameters based on the bond-order * beta matrix

PIMOVE Subroutine

"pimove"  rotates the  vector  between  atoms "list(1)"  and 
"list(2)" so that  atom 1 is at the origin  and atom 2 along 
the  x-axis; the  atoms defining  the respective  planes are 
also moved and their bond lengths normalized

PIPLANE Subroutine

"piplane" selects  the three  atoms which specify  the plane 
perpendicular to  each p-orbital;  the current  version will 
fail in certain situations,  including ketenes, allenes, and 
isolated or adjacent triple bonds

PISCF Subroutine

"piscf" performs  an scf  molecular orbital  calculation for 
the pisystem using a modified Pariser-Parr-Pople method

PITILT Subroutine

"pitilt" calculates for each pibond  the ratio of the actual 
p-orbital overlap integral to the  ideal overlap if the same 
orbitals were perfectly parallel

PLACE Subroutine

"place" finds  the probe sites  by putting the  probe sphere 
tangent to each triple of neighboring atoms

POLARGRP Subroutine

"polargrp" generates  members of  the polarization  group of 
each atom and  separate lists of the 1-2, 1-3  and 1-4 group 
connectivities

POLARIZE Program

"polarize" computes the molecular polarizability by applying 
an   external   field   along    each   axis   followed   by 
diagonalization of the resulting polarizability tensor

POLYMER Subroutine

"polymer"  tests for  the  presence of  an infinite  polymer 
extending across periodic boundaries

POLYP Subroutine

POTNRG Function

POTOFF Subroutine

"potoff" clears the forcefield definition by turning off the 
use of each of the potential energy functions

POWER Subroutine

"power" uses the power method  with deflation to compute the 
few  largest eigenvalues  and  eigenvectors  of a  symmetric 
matrix

PRECISE Function

"precise" finds a machine precision value as selected by the 
input  argument: (1)  the smallest  positive floating  point 
value, (2) the smallest relative floating point spacing, (3) 
the largest relative floating point spacing

PRECOND Subroutine

"precond"  solves   a  simplified  version  of   the  Newton 
equations Ms = r, and uses the result to precondition linear 
conjugate gradient  iterations on the full  Newton equations 
in "tnsolve"

PRESSURE Subroutine

"pressure" uses the internal virial  to find the pressure in 
a periodic box and maintains  a constant desired pressure by 
scaling the coordinates via coupling to an external constant 
pressure bath

PRMKEY Subroutine

"field" parses a text string  to extract keywords related to 
force field potential energy functional forms and constants

PROCHAIN Subroutine

"prochain" builds  up the internal coordinates  for an amino 
acid sequence from the phi, psi, omega and chi values

PROJCT Subroutine

PROMO Subroutine

"promo" writes a short  message containing information about 
the TINKER version number and the copyright notice

PROPERTY Function

"property" takes two input  snapshot frames and computes the 
value of the property for  which the correlation function is 
being accumulated

PROPYZE Subroutine

"propyze" finds  and prints the total  charge, dipole moment 
components, radius of gyration and moments of inertia

PROSIDE Subroutine

"proside"  builds the  side chain  for a  single amino  acid 
residue in terms of internal coordinates

PROTEIN Program

"protein" builds the internal and Cartesian coordinates of a 
polypeptide  from amino  acid sequence  and torsional  angle 
values for the peptide backbone and side chains

PRTDYN Subroutine

"prtdyn"  writes out  the  information needed  to restart  a 
molecular dynamics trajectory to an external disk file

PRTERR Subroutine

"prterr"  writes out  a set  of coordinates  to a  disk file 
prior to aborting on a serious error

PRTINT Subroutine

"prtint" writes  out a set of  Z-matrix internal coordinates 
to an external disk file

PRTMOL2 Program

"prtmol2"  writes out  a set  of coordinates  in Sybyl  MOL2 
format to an external disk file

PRTMSI Subroutine

"prtmsi" writes out  a set of Cartesian  coordinates for all 
active atoms in the MSI Insight II archive format

PRTPDB Subroutine

"prtpdb" writes out  a set of Protein  Data Bank coordinates 
to an external disk file

PRTPRM Subroutine

"prtprm" writes out  a formatted listing of  the default set 
of potential energy parameters for a force field

PRTSEQ Subroutine

"prtseq"  writes out  a biopolymer  sequence to  an external 
disk  file with  15 residues  per line  and distinct  chains 
separated by blank lines

PRTXMOL Subroutine

"prtxmol" writes out a set  of Cartesian coordinates for all 
active atoms in a simple,  generic XYZ format originally due 
to the XMOL program

PRTXYZ Subroutine

"prtxyz" writes  out a  set of  Cartesian coordinates  to an 
external disk file

PSS Program

"pss" implements the potential  smoothing plus search method 
for global  optimization in Cartesian coordinate  space with 
local searches performed in Cartesian or torsional space

PSS1 Function

"pss1" is  a service  routine that  computes the  energy and 
gradient  during   PSS  global  optimization   in  Cartesian 
coordinate space

PSS2 Subroutine

"pss2" is a service routine  that computes the sparse matrix 
Hessian elements during PSS global optimization in Cartesian 
coordinate space

PSSRGD1 Function

"pssrgd1" is a service routine  that computes the energy and 
gradient during PSS global optimization over rigid bodies

PSSRIGID Program

"pssrigid"  implements the  potential smoothing  plus search 
method for global optimization for a set of rigid bodies

PSSROT Program

"pssrot"  implements  the  potential smoothing  plus  search 
method for global optimization in torsional space

PSSROT1 Function

"pssrot1" is a service routine  that computes the energy and 
gradient during PSS global optimization in torsional space

PSSWRITE Subroutine

PTINCY Function

PZEXTR Subroutine

QRFACT Subroutine

"qrfact"  performs Householder  transformations with  column 
pivoting (optional) to  compute a QR factorization  of the m 
by n matrix  a; the routine determines  an orthogonal matrix 
q, a permutation matrix p, and an upper trapezoidal matrix r 
with diagonal elements of nonincreasing magnitude, such that 
a*p = q*r; the Householder  transformation for column k, k = 
1,2,...,min(m,n), is of the form

QRSOLVE Subroutine

"qrsolve" solves a*x=b and d*x=0 in the least squares sense; 
normally used in combination  with routine "qrfact" to solve 
least squares problems

QUATFIT Subroutine

"quatfit" uses a quaternion-based method to achieve the best 
fit superposition of two sets of coordinates

RADIAL Program

"radial"  finds  the  radial  distribution  function  for  a 
specified pair of atom types via analysis of a set of stored 
coordinate frames from a liquid simulation

RANDOM Function

"random"  generates a  random  number on  [0,1]  via a  long 
period generator due to L'Ecuyer with Bays-Durham shuffle

RANVEC Subroutine

"ranvec" generates a unit vector in 3-dimensional space with 
uniformly distributed random orientation

RATTLE Subroutine

"rattle"  implements   the  first  portion  of   the  rattle 
algorithm  by  correcting  atomic  positions  and  half-step 
velocities to maintain constrained interatomic distances

RATTLE2 Subroutine

"rattle2"  implements  the  second  portion  of  the  rattle 
algorithm by correcting the full-step velocities in order to 
maintain constrained interatomic distances

READBLK Subroutine

"readblk" reads  in a set  of snapshot frames  and transfers 
the values to internal arrays  for use in the computation of 
time correlation functions

READDYN Subroutine

"readdyn"  get the  positions, velocities  and accelerations 
for a molecular dynamics restart from an external disk file

READINT Subroutine

"readint" gets  a set of Z-matrix  internal coordinates from 
an external file

READMOL2 Subroutine

"readmol2"  gets a  set of  Sybyl MOL2  coordinates from  an 
external disk file

READPDB Subroutine

"readpdb" gets a  set of Protein Data  Bank coordinates from 
an external disk file

READPRM Subroutine

"readprm" processes  the potential energy parameter  file in 
order to define the default force field parameters

READSEQ Subroutine

"readseq" gets a biopolymer  sequence containing one or more 
separate chains from an  external file; all lines containing 
sequence must  begin with the starting  sequence number, the 
actual sequence is read from subsequent nonblank characters

READXYZ Subroutine

"readxyz"  gets  a  set  of Cartesian  coordinates  from  an 
external disk file

REFINE Subroutine

"refine" performs minimization of  the atomic coordinates of 
an initial crude embedded distance geometry structure versus 
the   bound,  chirality,   planarity  and   torsional  error 
functions

REGBODY Subroutine

"regbody" finds the angular velocity of a regular, nonlinear 
rigid body

REPLICA Subroutine

"replica"   decides  between   images  and   replicates  for 
generation  of periodic  boundary conditions,  and sets  the 
cell replicate list if the replicates method is to be used

RFINDEX Subroutine

RGDSRCH Subroutine

RGDSTEP Subroutine

"rgdstep" performs a single molecular dynamics time step for 
a rigid-body calculation

RIBOSOME Subroutine

"ribosome"  translates a  polypeptide  structure in  Protein 
Data Bank format to a Cartesian coordinate file and sequence 
file

RIGIDXYZ Subroutine

"rigidxyz" computes  Cartesian coordinates for a  rigid body 
group via rotation and translation of reference coordinates

RINGS Subroutine

"rings" searches  the structure  for small rings  and stores 
their component  atoms; code  to remove the  reducible rings 
consisting  of smaller  rings is  commented in  this version 
since reducible rings are needed for parameter assignment

RMSERROR Subroutine

"rmserror" computes  the maximum absolute deviation  and the 
rms deviation from  the distance bounds, and  the number and 
rms value of the distance restraint violations

RMSFIT Function

"rmsfit" computes the rms fit of two coordinate sets

ROTANG Function

ROTCHECK Function

"rotcheck" tests  a specified  candidate rotatable  bond for 
the disallowed case  where inactive atoms are  found on both 
sides of the candidate bond

ROTEULER Subroutine

"roteuler" computes  a set of Euler  angle values consistent 
with an input rotation matrix

ROTLIST Subroutine

"rotlist" generates the minimum list  of all the atoms lying 
to one side  of a pair of directly  bonded atoms; optionally 
finds the minimal list by choosing the side with fewer atoms

ROTMAT Subroutine

"rotmat"  find the  rotation matrix  that converts  from the 
local coordinate system at each multipole site to the global 
system

ROTPOLE Subroutine

"rotpole" computes the atomic multipole values in the global 
coordinate frame by  applying a rotation matrix to  a set of 
locally defined multipoles

ROTRGD Subroutine

"rotrgd" finds the rotation matrix for a rigid body due to a 
single step of dynamics

SADDLE Program

"saddle" finds a transition state between two conformational 
minima  using a  combination of  ideas from  the synchronous 
transit   (Halgren-Lipscomb)  and   quadratic  path   (Bell-
Crighton) methods

SADDLE1 Function

SADDLES Subroutine

"saddles" constructs circles, convex edges and saddle faces

SCAN Program

"scan" attempts to find all  the local minima on a potential 
energy surface via an iterative series of local searches

SCAN1 Function

"scan1" is  a service routine  that computes the  energy and 
gradient during  exploration of  a potential  energy surface 
via iterative local search

SCAN2 Subroutine

"scan2" is a service routine that computes the sparse matrix 
Hessian elements  during exploration  of a  potential energy 
surface via iterative local search

SDAREA Subroutine

"sdarea" optionally  scales the atomic  friction coefficient 
of each atom based on its accessible surface area

SDSTEP Subroutine

"sdstep" performs a single stochastic dynamics time step via 
a velocity Verlet integration algorithm

SDTERM Subroutine

"sdterm" gets  frictional and  random force terms  needed to 
update positions and velocities via stochastic dynamics

SEARCH Subroutine

"search"  is a  line search  minimizer based  upon parabolic 
extrapolation  and cubic  interpolation using  both function 
and  gradient  values; if  forced  to  search in  an  uphill 
direction, return is after the initial step

SETIME Subroutine

"setime" initializes the elapsed interval CPU timer

SHAKEUP Subroutine

"shakeup" initializes any holonomic constraints for use with 
the rattle algorithm during molecular dynamics

SIGMOID Function

"sigmoid" implements a normalized  sigmoidal function on the 
interval [0,1]; the curves connect (0,0) to (1,1) and have a 
cooperativity controlled  by beta, they approach  a straight 
line as beta -> 0 and get more nonlinear as beta increases

SLATER Subroutine

"slater"  is a  general  routine for  computing the  overlap 
integrals between two Slater-type orbitals

SMOOTH Subroutine

"smooth" sets  extent of  potential surface  deformation for 
use  with potential  smoothing  plus  search, the  diffusion 
equation method or Gaussian density annealing

SNIFFER Program

"sniffer"  performs a  global  energy  minimization using  a 
discrete version of Griewank's global search trajectory

SNIFFER1 Function

"sniffer1" is a service routine that computes the energy and 
gradient for the Sniffer global optimization method

SOAK Subroutine

"soak" takes a currently defined solute system and places it 
into a  solvent box, with  removal of any  solvent molecules 
that overlap the solute

SORT Subroutine

"sort" takes  an input  list of integers  and sorts  it into 
ascending order using the Heapsort algorithm

SORT2 Subroutine

"sort2"  takes an  input list  of  reals and  sorts it  into 
ascending  order  using  the  Heapsort  algorithm;  it  also 
returns a key into the original ordering

SORT3 Subroutine

"sort3" takes  an input list  of integers and sorts  it into 
ascending  order  using  the  Heapsort  algorithm;  it  also 
returns a key into the original ordering

SORT4 Subroutine

"sort4" takes  an input list  of integers and sorts  it into 
ascending absolute value using the Heapsort algorithm

SORT5 Subroutine

"sort5" takes  an input list  of integers and sorts  it into 
ascending order based on each value modulo "m"

SORT6 Subroutine

"sort6" takes an  input list of character  strings and sorts 
it into alphabetical order using the Heapsort algorithm

SORT7 Subroutine

"sort7" takes an  input list of character  strings and sorts 
it into alphabetical order  using the Heapsort algorithm; it 
also returns a key into the original ordering

SORT8 Subroutine

"sort8" takes  an input list  of integers and sorts  it into 
ascending  order  using  the Heapsort  algorithm,  duplicate 
values are removed from the final sorted list

SPACEFILL Program

"spacefill"  computes  the  surface  area and  volume  of  a 
structure;  the  van  der  Waals,  accessible-excluded,  and 
contact-reentrant definitions are available

SPECTRUM Program

"spectrum" computes a power spectrum over a wavelength range 
from the velocity autocorrelation as a function of time

SQUARE Subroutine

"square" is  a nonlinear least squares  routine derived from 
the IMSL routine BCLSF and More's Minpack routine LMDER; the 
Jacobian is  estimated by finite differences  and bounds can 
be specified for the variables to be refined

SUFFIX Subroutine

"suffix" checks a filename for the presence of an extension, 
and appends an extension if none is found

SUPERPOSE Program

"superpose" takes pairs of  structures and superimposes them 
in the optimal least squares sense; it will attempt to match 
all atom pairs or only those specified by the user

SURFACE Subroutine

"surface" performs an analytical computation of the weighted 
solvent accessible surface  area of each atom  and the first 
derivatives   of  the   area  with   respect  to   Cartesian 
coordinates

SURFATOM Subroutine

"surfatom" performs an analytical computation of the surface 
area of a specified atom; a simplified version of "surface"

SWITCH Subroutine

"switch" sets the coeffcients used  by the fifth and seventh 
order polynomial switching functions for spherical cutoffs

SYBYLXYZ Program

"sybylxyz"  takes as  input a  Sybyl MOL2  coordinates file, 
converts to and then writes out Cartesian coordinates

SYMMETRY Subroutine

"symmetry"  applies  symmetry  operators to  the  fractional 
coordinates of the asymmetric unit  in order to generate the 
symmetry related atoms of the full unit cell

TANGENT Subroutine

"tangent" finds  the projected  gradient on  the synchronous 
transit path for a point along the transit pathway

TEMPER Subroutine

"temper" maintains a constant desired temperature via either 
Berendsen's   velocity  scaling   coupled  to   an  external 
temperature bath or Andersen's stochastic collision method

TESTGRAD Program

"testgrad"   computes  and   compares  the   analytical  and 
numerical gradient vectors of  the potential energy function 
with respect to Cartesian coordinates

TESTHESS Program

"testhess"   computes  and   compares  the   analytical  and 
numerical Hessian matrices of  the potential energy function 
with respect to Cartesian coordinates

TESTLIGHT Program

"testlight" performs  a set of  timing tests to  compare the 
evaluation of potential energy and energy/gradient using the 
method of lights with a double loop over all atom pairs

TESTROT Program

"testrot" computes and compares the analytical and numerical 
gradient  vectors  of  the potential  energy  function  with 
respect to rotatable torsional angles

TIMER Program

"timer" measures the CPU time  required for file reading and 
parameter assignment,  potential energy  computation, energy 
and gradient computation, and Hessian matrix evaluation

TIMEROT Program

"timerot" measures  the CPU  time required for  file reading 
and  parameter  assignment,  potential  energy  computation, 
energy  and  gradient  over torsions,  and  torsional  angle 
Hessian matrix evaluation

TNCG Subroutine

"tncg" implements a  truncated Newton optimization algorithm 
in which  a preconditioned linear conjugate  gradient method 
is used  to approximately solve Newton's  equations; special 
features  include  use  of  an explicit  sparse  Hessian  or 
finite-difference gradient-Hessian  products within  the PCG 
iteration; the  exact Newton  search directions can  be used 
optionally;  by default  the algorithm  checks for  negative 
curvature  to  prevent  convergence to  a  stationary  point 
having negative  eigenvalues; if  a saddle point  is desired 
this test can be removed by disabling "negtest"

TNSOLVE Subroutine

"tnsolve" uses a linear conjugate gradient method to find an 
approximate  solution   to  the  set  of   linear  equations 
represented in matrix form by Hp = -g (Newton's equations)

TORPHASE Subroutine

"torphase" sets  the n-fold  amplitude and phase  values for 
each torsion via sorting of the input parameters

TORQUE Subroutine

"torque" takes the  torque values on sites  defined by local 
coordinate frames and distributes  thme to convert to forces 
on the original sites and sites specifying the local frames

TORQUE1 Subroutine

"torque1"  takes the  torque value  on a  site defined  by a 
local  coordinate frame  and  distributes it  to convert  to 
forces on the  original site and sites  specifying the local 
frame

TORSER Function

"torser" computes the torsional error function and its first 
derivatives with respect to the atomic Cartesian coordinates 
based on  the deviation  of specified torsional  angles from 
desired  values,   the  contained   bond  angles   are  also 
restrained to avoid a numerical instability

TORSIONS Subroutine

"torsions" finds the total number of dihedral angles and the 
numbers of the four atoms defining each dihedral angle

TORUS Subroutine

"torus" sets a list of  all of the temporary torus positions 
by testing for a torus between each atom and its neighbors

TOTERR Function

"toterr"  is  the  error  function  and  derivatives  for  a 
distance geometry embedding; it includes components from the 
distance  bounds,  hard  sphere  contacts,  local  geometry, 
chirality and torsional restraint errors

TRANSIT Function

"transit"  evaluates the  synchronous  transit function  and 
gradient; linear and quadratic transit paths are available

TRIANGLE Subroutine

"triangle" smooths  the upper and lower  distance bounds via 
the triangle  inequality using a full-matrix  variant of the 
Floyd-Warshall  shortest  path  algorithm; this  routine  is 
usually  much slower  than the  sparse matrix  shortest path 
methods in "geodesic" and "trifix",  and should be used only 
for comparison with answers generated by those routines

TRIFIX Subroutine

"trifix" rebuilds  both the  upper and lower  distance bound 
matrices following tightening  of one or both  of the bounds 
between  a specified  pair of  atoms, "p"  and "q",  using a 
modification of Murchland's shortest path update algorithm

TRIMTEXT Function

"trimtext" finds and  returns the location of  the last non-
blank character before the first  null character in an input 
text string; the function returns  zero if no such character 
is found

TRIPLE Function

"triple" finds the triple product  of three vectors; used as 
a service  routine by the  Connolly surface area  and volume 
computation

TRUST Subroutine

"trust" updates the model trust region for a nonlinear least 
squares  calculation; this  version  is based  on the  ideas 
found in NL2SOL and in Dennis and Schnabel's book

UDIRECT1 Subroutine

"udirect1" computes the reciprocal space contribution of the 
permanent  atomic  multipole  moments to  the  electrostatic 
field for use  in finding the direct  induced dipole moments 
via a regular Ewald summation

UDIRECT2 Subroutine

"udirect2"  computes  the  real space  contribution  of  the 
permanent  atomic  multipole  moments to  the  electrostatic 
field for use  in finding the direct  induced dipole moments 
via a regular Ewald summation

UFIELD Subroutine

"ufield" finds the field at each polarizable site due to the 
induced dipoles at  the other sites using  Thole's method to 
damp the field at close range

UMUTUAL1 Subroutine

"umutual1" computes the reciprocal space contribution of the 
induced atomic dipole moments to the electrostatic field for 
use in iterative calculation of induced dipole moments via a 
regular Ewald summation

UMUTUAL2 Subroutine

"umutual2"  computes  the  real space  contribution  of  the 
induced atomic dipole moments to the electrostatic field for 
use in iterative calculation of induced dipole moments via a 
regular Ewald summation

UNITCELL Subroutine

"unitcell" gets  the periodic boundary box  size and related 
values from an external keyword file

UPCASE Subroutine

"upcase" converts a text string to all upper case letters

VAM Subroutine

"vam" takes  the analytical  molecular surface defined  as a 
collection of spherical and toroidal polygons and uses it to 
compute the volume and surface area

VCROSS Subroutine

"vcross" finds the cross product of two vectors

VDWERR Function

"vdwerr"  is  the hard  sphere  van  der Waals  bound  error 
function  and  derivatives  that penalizes  close  nonbonded 
contacts, pairwise neighbors are generated via the method of 
lights

VECANG Function

"vecang"  finds the  angle between  two vectors  handed with 
respect to a coordinate axis;  returns an angle in the range 
[0,2*pi]

VERLET Subroutine

"verlet" performs  a single molecular dynamics  time step by 
means of the velocity Verlet multistep recursion formula

VERSION Subroutine

"version" checks the  name of a file about to  be opened; if 
if "old" status  is passed, the name of  the highest current 
version is returned; if "new"  status is passed the filename 
of the next available unused version is generated

VIBRATE Program

"vibrate" performs  a vibrational normal mode  analysis; the 
Hessian matrix of second  derivatives is determined and then 
diagonalized both directly and  after mass weighting; output 
consists of the eigenvalues of  the force constant matrix as 
well as the vibrational frequencies and displacements

VIBROT Program

VNORM Subroutine

"vnorm"  normalizes  a vector  to  unit  length; used  as  a 
service  routine by  the  Connolly surface  area and  volume 
computation

VOLUME Subroutine

"volume"  calculates the  excluded volume  via the  Connolly 
analytical volume and surface area algorithm

VOLUME1 Subroutine

"volume1" calculates first derivatives of the total excluded 
volume  with respect  to the  Cartesian coordinates  of each 
atom

VOLUME2 Subroutine

"volume2"  calculates   second  derivatives  of   the  total 
excluded volume with respect to the Cartesian coordinates of 
the atoms

WATSON Subroutine

"watson"  uses a  rigid-body  optimization to  approximately 
align the paired strands of a nucleic acid double helix

WATSON1 Function

"watson1" is a service routine  that computes the energy and 
gradient   for   optimally   conditioned   variable   metric 
optimization of rigid bodies

WRITEOUT Subroutine

"writeout" is used  by each of the  optimization routines to 
save imtermediate atomic coordinates to a disk file

XTALERR Subroutine

XTALFIT Program

"xtalfit"  computes an  optimized  set  of potential  energy 
parameters   for   user   specified  van   der   Waals   and 
electrostatic interactions by  fitting to crystal structure, 
lattice energy and monomer dipole moment data

XTALLAT1 Function

"xtalmol1" is a service routine that computes the energy and 
numerical gradient  with respect to the  six lattice lengths 
and angles for a crystal energy minimization

XTALMIN Program

"xtalmin"  performs a  full crystal  energy minimization  by 
alternating  cycles of  truncated  Newton optimization  over 
atomic  coordinates with  variable metric  optimization over 
the six lattice dimensions and angles

XTALMOL1 Function

"xtalmol1" is a service routine that computes the energy and 
gradient with  respect to  the atomic  Cartesian coordinates 
for a crystal energy minimization

XTALMOL2 Subroutine

"xtalmol2"  is a  service routine  that computes  the sparse 
matrix Hessian elements with respect to the atomic Cartesian 
coordinates for a crystal energy minimization

XTALMOVE Subroutine

XTALPRM Subroutine

"xtalprm" stores  or retrieves a crystal  structure; used to 
make  a previously  stored  structure  the currently  active 
structure, or to  store a structure for later  use; only the 
intermolecular energy terms are provided for

XTALWRT Subroutine

XYZATM Subroutine

"xyzatm" computes the Cartesian coordinates of a single atom 
from its defining internal coordinate values

XYZEDIT Program

"xyzedit" provides for modification  and manipulation of the 
contents of a Cartesian coordinates file

XYZINT Program

"xyzint" takes  as input a Cartesian  coordinates file, then 
converts to and writes out an internal coordinates file

XYZPDB Program

"xyzpdb" takes  as input a Cartesian  coordinates file, then 
converts to and writes out a Protein Data Bank file

XYZRIGID Subroutine

"xyzrigid" computes the center of mass and Euler angle rigid 
body coordinates for each atom group in the system

XYZSYBYL Program

"xyzsybyl"  takes as  input  a  Cartesian coordinates  file, 
converts to and then writes out a Sybyl MOL2 file

ZATOM Subroutine

"zatom" adds an atom to the  end of the current Z-matrix and 
then increments the atom  counter; atom type, defining atoms 
and internal coordinates are passed as arguments

ZHELP Subroutine

"zhelp" prints the general  information and instructions for 
the Z-matrix editing program

ZVALUE Subroutine

"zvalue" gets user supplied  values for selected coordinates 
as needed by the internal coordinate editing program
 10.    Contents of Common Block Variables

     The Fortran  common blocks found in  the TINKER package 
are  listed below  along  with a  brief  description of  the 
contents  of  each  variable  in  each  common  block.  Each 
individual common block  is present as a  separate ".i" file 
in  the   /source  subdirectory.   A  source   code  listing 
containing each of  the source code modules and  each of the 
common blocks can be  produced by running the "listing.make" 
script found in the distribution.

ACTION              total number of each energy term 
computed

neb                 number of bond stretch energy terms 
computed
nea                 number of angle bend energy terms 
computed
neba                number of stretch-bend energy terms 
computed
neub                number of Urey-Bradley energy terms 
computed
neaa                number of angle-angle energy terms 
computed
neopb               number of out-of-plane bend energy terms 
computed
neopd               number of out-of-plane distance energy 
terms computed
neid                number of improper dihedral energy terms 
computed
neit                number of improper torsion energy terms 
computed
net                 number of torsional energy terms 
computed
nebt                number of stretch-torsion energy terms 
computed
nett                number of torsion-torsion energy terms 
computed
nev                 number of van der Waals energy terms 
computed
nec                 number of charge-charge energy terms 
computed
necd                number of charge-dipole energy terms 
computed
ned                 number of dipole-dipole energy terms 
computed
nem                 number of multipole energy terms 
computed
nep                 number of polarization energy terms 
computed
new                 number of Ewald summation energy terms 
computed
ner                 number of reaction field energy terms 
computed
nes                 number of solvation energy terms 
computed
nelf                number of metal ligand field energy 
terms computed
neg                 number of geometric restraint energy 
terms computed
nex                 number of extra energy terms computed

ALIGN               information for superposition of 
structures

wfit                weights assigned to atom pairs during 
superposition
nfit                number of atoms to use in superimposing 
two structures
ifit                atom numbers of pairs of atoms to be 
superimposed

ANALYZ              energy components partitioned over atoms

aeb                 bond stretch energy partitioned over 
atoms
aea                 angle bend energy partitioned over atoms
aeba                stretch-bend energy partitioned over 
atoms
aeub                Urey-Bradley energy partitioned over 
atoms
aeaa                angle-angle energy partitioned over 
atoms
aeopb               out-of-plane bend energy partitioned 
over atoms
aeopd               out-of-plane distance energy partitioned 
over atoms
aeid                improper dihedral energy partitioned 
over atoms
aeit                improper torsion energy partitioned over 
atoms
aet                 torsional energy partitioned over atoms
aebt                stretch-torsion energy partitioned over 
atoms
aett                torsion-torsion energy partitioned over 
atoms
aev                 van der Waals energy partitioned over 
atoms
aec                 charge-charge energy partitioned over 
atoms
aecd                charge-dipole energy partitioned over 
atoms
aed                 dipole-dipole energy partitioned over 
atoms
aem                 multipole energy partitioned over atoms
aep                 polarization energy partitioned over 
atoms
aer                 reaction field energy partitioned over 
atoms
aes                 solvation energy partitioned over atoms
aelf                metal ligand field energy partitioned 
over atoms
aeg                 geometric restraint energy partitioned 
over atoms
aex                 extra energy term partitioned over atoms

ANGANG              angle-angle terms in current structure

kaa                 force constant for angle-angle cross 
terms
nangang             total number of angle-angle interactions
iaa                 angle numbers used in each angle-angle 
term

ANGLE               bond angles within the current structure

ak                  harmonic angle force constant 
(kcal/mole/rad**2)
anat                ideal bond angle or phase shift angle 
(degrees)
afld                periodicity for Fourier bond angle term
nangle              total number of bond angles in the 
system
iang                numbers of the atoms in each bond angle
angtyp              potential energy function type for each 
bond angle

ANGPOT              specifics of bond angle functional forms

cang                cubic coefficient in angle bending 
potential
qang                quartic coefficient in angle bending 
potential
pang                quintic coefficient in angle bending 
potential
sang                sextic coefficient in angle bending 
potential
angunit             convert angle force constant to 
kcal/mole/deg**2
stbnunit            convert str-bend constant to 
kcal/mole/deg-Ang**2
aaunit              convert angle-angle constant to 
kcal/mole/deg**2
opbunit             convert out-of-plane bend force to 
kcal/mole/deg**2
opdunit             convert out-of-plane distance to 
kcal/mole/Ang**2
mm2stbn             logical flag governing use of MM2-style 
stretch-bend

ARGUE               command line arguments at program 
startup

maxarg              maximum number of command line arguments
narg                number of command line arguments to the 
program
listarg             flag to mark available command line 
arguments
arg                 strings containing the command line 
arguments

ATMLST              local geometry terms involving each atom

bndlist             list of the bond numbers involving each 
atom
anglist             list of the angle numbers centered on 
each atom

ATMTYP              atomic properties for each current atom

mass                atomic weight for each atom in the 
system
tag                 integer atom labels from input 
coordinates file
class               atom class number for each atom in the 
system
atomic              atomic number for each atom in the 
system
valence             valence number for each atom in the 
system
name                atom name for each atom in the system
story               descriptive type for each atom in system

ATOMS               number, position and type of current 
atoms

x                   current x-coordinate for each atom in 
the system
y                   current y-coordinate for each atom in 
the system
z                   current z-coordinate for each atom in 
the system
n                   total number of atoms in the current 
system
type                atom type number for each atom in the 
system

BATH                temperature and pressure control 
parameters

kelvin              target value for the system temperature 
(K)
atmsph              target value for the system pressure 
(atm)
tautemp             time constant in psec for temperature 
bath coupling
taupres             time constant in psec for pressure bath 
coupling
compress            isothermal compressibility of medium 
(atm-1)
collide             collision frequency for Andersen 
thermostat
isothermal          logical flag geverning use of 
temperature bath
isobaric            logical flag governing use of pressure 
bath
thermostat          type of thermostat, either Berendsen or 
Andersen

BNDPOT              specifics of bond stretch functional 
forms

cbnd                cubic coefficient in bond stretch 
potential
qbnd                quartic coefficient in bond stretch 
potential
bndunit             convert bond force constant to 
kcal/mole/Ang**2
bndtyp              type of bond stretch potential energy 
function

BOND                covalent bonds in the current structure

bk                  bond stretch force constants 
(kcal/mole/Ang**2)
bl                  ideal bond length values in Angstroms
nbond               total number of bond stretches in the 
system
ibnd                numbers of the atoms in each bond 
stretch

BORDER              bond orders for a conjugated pisystem

pbpl                pi-bond orders for bonds in "planar" 
pisystem
pnpl                pi-bond orders for bonds in "nonplanar" 
pisystem

BOUND               control of periodic boundary conditions

polycut             cutoff distance for infinite polymer 
nonbonds
polycut2            square of infinite polymer nonbond 
cutoff
use_bounds          flag to use periodic boundary conditions
use_image           flag to use images for periodic system
use_replica         flag to use replicates for periodic 
system
use_polymer         flag to mark presence of infinite 
polymer

BOXES               parameters for periodic boundary 
conditions

xbox                length in Angs of a-axis of periodic box
ybox                length in Angs of b-axis of periodic box
zbox                length in Angs of c-axis of periodic box
alpha               angle in degrees between b- and c-axes 
of box
beta                angle in degrees between a- and c-axes 
of box
gamma               angle in degrees between a- and b-axes 
of box
xbox2               half of the a-axis length of periodic 
box
ybox2               half of the b-axis length of periodic 
box
zbox2               half of the c-axis length of periodic 
box
box34               three-fourths axis length of truncated 
octahedron
recip               reciprocal lattice vectors as matrix 
columns
volbox              volume in Ang**3 of the periodic box
beta_sin            sine of the beta periodic box angle
beta_cos            cosine of the beta periodic box angle
gamma_sin           sine of the gamma periodic box angle
gamma_cos           cosine of the gamma periodic box angle
beta_term           term used in generating triclinic box
gamma_term          term used in generating triclinic box
orthogonal          flag to mark periodic box as orthogonal
monoclinic          flag to mark periodic box as monoclinic
triclinic           flag to mark periodic box as triclinic
octahedron          flag to mark box as truncated octahedron
spacegrp            space group symbol for the unitcell type

CELL                periodic boundaries using replicated 
cells

xcell               length of the a-axis of the complete 
replicated cell
ycell               length of the b-axis of the complete 
replicated cell
zcell               length of the c-axis of the complete 
replicated cell
xcell2              half the length of the a-axis of the 
replicated cell
ycell2              half the length of the b-axis of the 
replicated cell
zcell2              half the length of the c-axis of the 
replicated cell
ncell               total number of cell replicates for 
periodic boundaries
icell               offset along axes for each replicate 
periodic cell

CENTRE              atom coordinates relative to center of 
mass

xcm                 offset of each atom from center of mass 
x-coordinate
ycm                 offset of each atom from center of mass 
y-coordinate
zcm                 offset of each atom from center of mass 
z-coordinate

CHARGE              partial charges for the current 
structure

pchg                magnitude of the partial charges (e-)
nion                total number of partial charges in 
system
iion                number of the atom site for each partial 
charge
jion                neighbor generation site for each 
partial charge
kion                cutoff switching site for each partial 
charge
chglist             partial charge site for each atom (0=no 
charge)

CHGPOT              specifics of charge-charge functional 
form

dielec              dielectric constant for electrostatic 
interactions
c2scale             factor by which 1-2 charge interactions 
are scaled
c3scale             factor by which 1-3 charge interactions 
are scaled
c4scale             factor by which 1-4 charge interactions 
are scaled
c5scale             factor by which 1-5 charge interactions 
are scaled
neutnbr             logical flag governing use of neutral 
group neighbors
neutcut             logical flag governing use of neutral 
group cutoffs

CHRONO              timing statistics for the current 
program

cputim              elapsed cpu time in seconds since start 
of program

COUPLE              near-neighbor atom connectivity lists

maxn13              maximum number of atoms 1-3 connected to 
an atom
maxn14              maximum number of atoms 1-4 connected to 
an atom
maxn15              maximum number of atoms 1-5 connected to 
an atom
n12                 number of atoms directly bonded to each 
atom
i12                 atom numbers of atoms 1-2 connected to 
each atom
n13                 number of atoms in a 1-3 relation to 
each atom
i13                 atom numbers of atoms 1-3 connected to 
each atom
n14                 number of atoms in a 1-4 relation to 
each atom
i14                 atom numbers of atoms 1-4 connected to 
each atom
n15                 number of atoms in a 1-5 relation to 
each atom
i15                 atom numbers of atoms 1-5 connected to 
each atom

CUTOFF              cutoff distances for energy interactions

vdwcut              cutoff distance for van der Waals 
interactions
chgcut              cutoff distance for charge-charge 
interactions
dplcut              cutoff distance for dipole-dipole 
interactions
mpolecut            cutoff distance for atomic multipole 
interactions
vdwtaper            distance at which van der Waals 
switching begins
chgtaper            distance at which charge-charge 
switching begins
dpltaper            distance at which dipole-dipole 
switching begins
mpoletaper          distance at which atomic multipole 
switching begins
ewaldcut            cutoff distance for direct space Ewald 
summation
use_ewald           logical flag governing use of Ewald 
summation term
use_lights          logical flag to use method of lights 
neighbors

DERIV               Cartesian coordinate derivative 
components

deb                 bond stretch Cartesian coordinate 
derivatives
dea                 angle bend Cartesian coordinate 
derivatives
deba                stretch-bend Cartesian coordinate 
derivatives
deub                Urey-Bradley Cartesian coordinate 
derivatives
deaa                angle-angle Cartesian coordinate 
derivatives
deopb               out-of-plane bend Cartesian coordinate 
derivatives
deopd               out-of-plane distance Cartesian 
coordinate derivatives
deid                improper dihedral Cartesian coordinate 
derivatives
deit                improper torsion Cartesian coordinate 
derivatives
det                 torsional Cartesian coordinate 
derivatives
debt                stretch-torsion Cartesian coordinate 
derivatives
dett                torsion-torsion Cartesian coordinate 
derivatives
dev                 van der Waals Cartesian coordinate 
derivatives
dec                 charge-charge Cartesian coordinate 
derivatives
decd                charge-dipole Cartesian coordinate 
derivatives
ded                 dipole-dipole Cartesian coordinate 
derivatives
dem                 multipole Cartesian coordinate 
derivatives
dep                 polarization Cartesian coordinate 
derivatives
der                 reaction field Cartesian coordinate 
derivatives
des                 solvation Cartesian coordinate 
derivatives
delf                metal ligand field Cartesian coordinate 
derivatives
deg                 geometric restraint Cartesian coordinate 
derivatives
dex                 extra energy term Cartesian coordinate 
derivatives

DIPOLE              atom & bond dipoles for current 
structure

bdpl                magnitude of each of the dipoles 
(Debyes)
sdpl                position of each dipole between defining 
atoms
ndipole             total number of dipoles in the system
idpl                numbers of atoms that define each dipole

DISGEO              distance geometry bounds and parameters

bnd                 distance geometry upper and lower bounds 
matrix
vdwrad              hard sphere radii for distance geometry 
atoms
vchir               signed volume values for chirality 
constraints
compact             index of local distance compaction on 
embedding
pathmax             maximum value of upper bound after 
smoothing
vdwmax              maximum value of hard sphere sum for an 
atom pair
nchir               total number of chirality constraints
ichir               numbers of atoms in each chirality 
constraint
use_invert          flag to use enantiomer closest to input 
structure
use_anneal          flag to use simulated annealing 
refinement

DOMEGA              derivative components over dihedrals

teb                 bond stretch derivatives over torsions
tea                 angle bend derivatives over torsions
teba                stretch-bend derivatives over torsions
teub                Urey-Bradley derivatives over torsions
teaa                angle-angle derivatives over torsions
teopb               out-of-plane bend derivatives over 
torsions
teopd               out-of-plane distance derivatives over 
torsions
teid                improper dihedral derivatives over 
torsions
teit                improper torsion derivatives over 
torsions
tet                 torsional derivatives over torsions
tebt                stretch-torsion derivatives over 
torsions
tett                torsion-torsion derivatives over 
torsions
tev                 van der Waals derivatives over torsions
tec                 charge-charge derivatives over torsions
tecd                charge-dipole derivatives over torsions
ted                 dipole-dipole derivatives over torsions
tem                 atomic multipole derivatives over 
torsions
tep                 polarization derivatives over torsions
ter                 reaction field derivatives over torsions
tes                 solvation derivatives over torsions
telf                metal ligand field derivatives over 
torsions
teg                 geometric restraint derivatives over 
torsions
tex                 extra energy term derivatives over 
torsions

ENERGI              individual potential energy components

eb                  bond stretch potential energy of the 
system
ea                  angle bend potential energy of the 
system
eba                 stretch-bend potential energy of the 
system
eub                 Urey-Bradley potential energy of the 
system
eaa                 angle-angle potential energy of the 
system
eopb                out-of-plane bend potential energy of 
the system
eopd                out-of-plane distance potential energy 
of the system
eid                 improper dihedral potential energy of 
the system
eit                 improper torsion potential energy of the 
system
et                  torsional potential energy of the system
ebt                 stretch-torsion potential energy of the 
system
ett                 torsion-torsion potential energy of the 
system
ev                  van der Waals potential energy of the 
system
ec                  charge-charge potential energy of the 
system
ecd                 charge-dipole potential energy of the 
system
ed                  dipole-dipole potential energy of the 
system
em                  atomic multipole potential energy of the 
system
ep                  polarization potential energy of the 
system
er                  reaction field potential energy of the 
system
es                  solvation potential energy of the system
elf                 metal ligand field potential energy of 
the system
eg                  geometric restraint potential energy of 
the system
ex                  extra term potential energy of the 
system

EWALD               parameters for regular or PM Ewald 
summation

aewald              Ewald convergence coefficient value 
(Ang-1)
frecip              fractional cutoff value for reciprocal 
sphere
tinfoil             flag governing use of tinfoil boundary 
conditions

EWREG               exponential factors for regular Ewald 
sum

maxvec              maximum number of k-vectors per 
reciprocal axis
ejc                 exponental factors for cosine along the 
j-axis
ejs                 exponental factors for sine along the j-
axis
ekc                 exponental factors for cosine along the 
k-axis
eks                 exponental factors for sine along the k-
axis
elc                 exponental factors for cosine along the 
l-axis
els                 exponental factors for sine along the l-
axis

FACES               variables for Connolly area and volume

maxnbr              maximum number of neighboring atom pairs
maxtt               maximum number of temporary tori
maxt                maximum number of total tori
maxp                maximum number of probe positions
maxv                maximum number of vertices
maxen               maximum number of concave edges
maxfn               maximum number of concave faces
maxc                maximum number of circles
maxep               maximum number of convex edges
maxfs               maximum number of saddle faces
maxcy               maximum number of cycles
mxcyep              maximum number of cycle convex edges
maxfp               maximum number of convex faces
mxfpcy              maximum number of convex face cycles

FIELDS              molecular mechanics force field 
description

biotyp              force field atom type of each biopolymer 
type
forcefield          string used to describe the current 
forcefield

FILES               name and number of current structure 
files

nprior              number of previously existing cycle 
files
ldir                length in characters of the directory 
name
leng                length in characters of the base 
filename
filename            base filename used by default for all 
files
outfile             output filename used for intermediate 
results

FRACS               atom distances to molecular center of 
mass

xfrac               fractional coordinate along a-axis of 
center of mass
yfrac               fractional coordinate along b-axis of 
center of mass
zfrac               fractional coordinate along c-axis of 
center of mass

GROUP               partitioning of system into atom groups

grpmass             total mass of all the atoms in each 
group
wgrp                weight for each set of group-group 
interactions
grpnum              original group number for each nonempty 
group
ngrp                total number of atom groups in the 
system
kgrp                contiguous list of the atoms in each 
group
igrp                first and last atom of each group in the 
list
grplist             number of the group to which each atom 
belongs
use_group           flag to use partitioning of system into 
groups
use_intra           flag to include only intragroup 
interactions
use_inter           flag to include only intergroup 
interactions

HESCUT              cutoff value for Hessian matrix elements

hesscut             magnitude of smallest allowed Hessian 
element

HESSN               Cartesian Hessian elements for a single 
atom

hessx               Hessian elements for x-component of 
current atom
hessy               Hessian elements for y-component of 
current atom
hessz               Hessian elements for z-component of 
current atom

IMPROP              improper dihedrals in the current 
structure

kprop               force constant values for improper 
dihedral angles
vprop               ideal improper dihedral angle value in 
degrees
niprop              total number of improper dihedral angles 
in the system
iiprop              numbers of the atoms in each improper 
dihedral angle

IMPTOR              improper torsions in the current 
structure

itors1              1-fold amplitude and phase for each 
improper torsion
itors2              2-fold amplitude and phase for each 
improper torsion
itors3              3-fold amplitude and phase for each 
improper torsion
nitors              total number of improper torsional 
angles in the system
iitors              numbers of the atoms in each improper 
torsional angle

INFORM              control values for I/O and program flow

digits              decimal places output for energy and 
coordinates
iprint              steps between status printing (0=no 
printing)
iwrite              steps between coordinate dumps (0=no 
dumps)
verbose             logical flag to turn on extra 
information
debug               logical flag to turn on full debug 
printing
holdup              logical flag to wait for carriage return 
on exit
abort               logical flag to stop execution at next 
chance

INTER               sum of intermolecular energy components

einter              total intermolecular potential energy

IOUNIT              Fortran input/output (I/O) unit numbers

iout                Fortran I/O unit for major output 
(default=6)
input               Fortran I/O unit for major input 
(default=5)

KANANG              forcefield parameters for angle-angle 
terms

anan                angle-angle cross term parameters for 
each atom class

KANGS               forcefield parameters for bond angle 
bending

maxna               maximum number of harmonic angle bend 
parameter entries
maxna5              maximum number of 5-membered ring angle 
bend entries
maxna4              maximum number of 4-membered ring angle 
bend entries
maxna3              maximum number of 3-membered ring angle 
bend entries
maxnaf              maximum number of Fourier angle bend 
parameter entries
acon                force constant parameters for harmonic 
angle bends
acon5               force constant parameters for 5-ring 
angle bends
acon4               force constant parameters for 4-ring 
angle bends
acon3               force constant parameters for 3-ring 
angle bends
aconf               force constant parameters for Fourier 
angle bends
ang                 bond angle parameters for harmonic angle 
bends
ang5                bond angle parameters for 5-ring angle 
bends
ang4                bond angle parameters for 4-ring angle 
bends
ang3                bond angle parameters for 3-ring angle 
bends
angf                phase shift angle and periodicity for 
Fourier bends
ka                  string of atom classes for harmonic 
angle bends
ka5                 string of atom classes for 5-ring angle 
bends
ka4                 string of atom classes for 4-ring angle 
bends
ka3                 string of atom classes for 3-ring angle 
bends
kaf                 string of atom classes for Fourier angle 
bends

KATOMS              forcefield parameters for the atom types

weight              average atomic mass of each atom type
atmcls              atom class number for each of the atom 
types
atmnum              atomic number for each of the atom types
ligand              number of atoms to be attached to each 
atom type
symbol              modified atomic symbol for each atom 
type
describe            string identifing each of the atom types

KBONDS              forcefield parameters for bond 
stretching

maxnb               maximum number of bond stretch parameter 
entries
maxnb5              maximum number of 5-membered ring bond 
stretch entries
maxnb4              maximum number of 4-membered ring bond 
stretch entries
maxnb3              maximum number of 3-membered ring bond 
stretch entries
maxnel              maximum number of electronegativity bond 
corrections
bcon                force constant parameters for harmonic 
bond stretch
bcon5               force constant parameters for 5-ring 
bond stretch
bcon4               force constant parameters for 4-ring 
bond stretch
bcon3               force constant parameters for 3-ring 
bond stretch
blen                bond length parameters for harmonic bond 
stretch
blen5               bond length parameters for 5-ring bond 
stretch
blen4               bond length parameters for 4-ring bond 
stretch
blen3               bond length parameters for 3-ring bond 
stretch
dlen                electronegativity bond length correction 
parameters
kb                  string of atom classes for harmonic bond 
stretch
kb5                 string of atom classes for 5-ring bond 
stretch
kb4                 string of atom classes for 4-ring bond 
stretch
kb3                 string of atom classes for 3-ring bond 
stretch
kel                 string of atom classes for 
electronegativity corrections

KCHRGE              forcefield parameters for partial 
charges

chg                 partial charge parameters for each atom 
type

KDIPOL              forcefield parameters for bond dipoles

maxnd               maximum number of bond dipole parameter 
entries
maxnd5              maximum number of 5-membered ring dipole 
entries
maxnd4              maximum number of 4-membered ring dipole 
entries
maxnd3              maximum number of 3-membered ring dipole 
entries
dpl                 dipole moment parameters for bond 
dipoles
dpl5                dipole moment parameters for 5-ring 
dipoles
dpl4                dipole moment parameters for 4-ring 
dipoles
dpl3                dipole moment parameters for 3-ring 
dipoles
pos                 dipole position parameters for bond 
dipoles
pos5                dipole position parameters for 5-ring 
dipoles
pos4                dipole position parameters for 4-ring 
dipoles
pos3                dipole position parameters for 3-ring 
dipoles
kd                  string of atom classes for bond dipoles
kd5                 string of atom classes for 5-ring 
dipoles
kd4                 string of atom classes for 4-ring 
dipoles
kd3                 string of atom classes for 3-ring 
dipoles

KEYS                contents of current keyword parameter 
file

nkey                number of nonblank lines in the keyword 
file
keyline             contents of each individual keyword file 
line

KGEOMS              parameters for the geometrical 
restraints

depth               depth of shallow Gaussian basin 
restraint
width               exponential width coefficient of 
Gaussian basin
rwall               radius of spherical droplet boundary 
restraint
xpfix               x-coordinate target for each restrained 
position
ypfix               y-coordinate target for each restrained 
position
zpfix               z-coordinate target for each restrained 
position
pfix                flat-well range and force constant for 
each position
dfix                target range and force constant for each 
distance
afix                target range and force constant for each 
angle
tfix                target range and force constant for each 
torsion
npfix               number of position restraints to be 
applied
ipfix               atom number involved in each position 
restraint
ndfix               number of distance restraints to be 
applied
idfix               atom numbers defining each distance 
restraint
nafix               number of angle restraints to be applied
iafix               atom numbers defining each angle 
restraint
ntfix               number of torsional restraints to be 
applied
itfix               atom numbers defining each torsional 
restraint
use_basin           logical flag governing use of Gaussian 
basin
use_wall            logical flag governing use of droplet 
boundary

KHBOND              forcefield parameters for H-bonding 
terms

maxnhb              maximum number of hydrogen bonding pair 
entries
radhb               radius parameter for hydrogen bonding 
pairs
epshb               well depth parameter for hydrogen 
bonding pairs
khb                 string of atom types for hydrogen 
bonding pairs

KIPROP              forcefield parameters for improper 
dihedral

maxndi              maximum number of improper dihedral 
parameter entries
dcon                force constant parameters for improper 
dihedrals
tdi                 ideal dihedral angle values for improper 
dihedrals
kdi                 string of atom classes for improper 
dihedral angles

KITORS              forcefield parameters for improper 
torsions

maxnti              maximum number of improper torsion 
parameter entries
ti1                 torsional parameters for improper 1-fold 
rotation
ti2                 torsional parameters for improper 2-fold 
rotation
ti3                 torsional parameters for improper 3-fold 
rotation
kti                 string of atom classes for improper 
torsional parameters

KMULTI              forcefield parameters for atomic 
multipoles

maxnmp              maximum number of atomic multipole 
parameter entries
multip              atomic monopole, dipole and quadrupole 
values
mpaxis              type of local axis definition for atomic 
multipoles
kmp                 string of atom types for atomic 
multipoles

KOPBND              forcefield parameters for out-of-plane 
bend

maxnopb             maximum number of out-of-plane bending 
entries
copb                force constant parameters for out-of-
plane bending
kaopb               string of atom classes for out-of-plane 
bending

KOPDST              forcefield parameters for out-plane 
distance

maxnopb             maximum number of out-of-plane distance 
entries
copb                force constant parameters for out-of-
plane distance
kaopb               string of atom classes for out-of-plane 
distance

KORBS               forcefield parameters for pisystem 
orbitals

maxnpi              maximum number of pisystem bond 
parameter entries
electron            number of pi-electrons for each atom 
class
ionize              ionization potential for each atom class
repulse             repulsion integral value for each atom 
class
sslope              slope for bond stretch vs. pi-bond order
tslope              slope for 2-fold torsion vs. pi-bond 
order
kpi                 string of atom classes for pisystem 
bonds

KPOLR               forcefield parameters for polarizability

polr                dipole polarizability parameters for 
each atom type
pgrp                connected types in polarization group of 
each atom type

KSTBND              forcefield parameters for stretch-
bending

stbn                stretch-bending parameters for each atom 
class

KSTTOR              forcefield parameters for stretch-
torsions

maxnbt              maximum number of stretch-torsion 
parameter entries
btcon               force constant parameters for stretch-
torsion
kbt                 string of atom classes for bonds in 
stretch-torsion

KTORSN              forcefield parameters for torsional 
angles

maxnt               maximum number of torsional angle 
parameter entries
maxnt5              maximum number of 5-membered ring 
torsion entries
maxnt4              maximum number of 4-membered ring 
torsion entries
t1                  torsional parameters for standard 1-fold 
rotation
t2                  torsional parameters for standard 2-fold 
rotation
t3                  torsional parameters for standard 3-fold 
rotation
t4                  torsional parameters for standard 4-fold 
rotation
t5                  torsional parameters for standard 5-fold 
rotation
t6                  torsional parameters for standard 6-fold 
rotation
t15                 torsional parameters for 1-fold rotation 
in 5-ring
t25                 torsional parameters for 2-fold rotation 
in 5-ring
t35                 torsional parameters for 3-fold rotation 
in 5-ring
t45                 torsional parameters for 4-fold rotation 
in 5-ring
t55                 torsional parameters for 5-fold rotation 
in 5-ring
t65                 torsional parameters for 6-fold rotation 
in 5-ring
t14                 torsional parameters for 1-fold rotation 
in 4-ring
t24                 torsional parameters for 2-fold rotation 
in 4-ring
t34                 torsional parameters for 3-fold rotation 
in 4-ring
t44                 torsional parameters for 4-fold rotation 
in 4-ring
t54                 torsional parameters for 5-fold rotation 
in 4-ring
t64                 torsional parameters for 6-fold rotation 
in 4-ring
kt                  string of atom classes for torsional 
angles
kt5                 string of atom classes for 5-ring 
torsions
kt4                 string of atom classes for 4-ring 
torsions

KURYBR              forcefield parameters for Urey-Bradley 
terms

maxnu               maximum number of Urey-Bradley parameter 
entries
ucon                force constant parameters for Urey-
Bradley terms
dst13               ideal 1-3 distance parameters for Urey-
Bradley terms
ku                  string of atom classes for Urey-Bradley 
terms

KVDWPR              forcefield parameters for special vdw 
terms

maxnvp              maximum number of special van der Waals 
pair entries
radpr               radius parameter for special van der 
Waals pairs
epspr               well depth parameter for special van der 
Waals pairs
kvpr                string of atom classes for special van 
der Waals pairs

KVDWS               forcefield parameters for van der Waals 
terms

rad                 van der Waals radius parameter for each 
atom class
eps                 van der Waals well depth parameter for 
each atom class
rad4                van der Waals radius parameter in 1-4 
interactions
eps4                van der Waals well depth parameter in 1-
4 interactions
reduct              van der Waals reduction factor for each 
atom class

LIGHT               indices for method of lights pair 
neighbors

nlight              total number of sites for method of 
lights calculation
kbx                 low index of neighbors of each site in 
the x-sorted list
kby                 low index of neighbors of each site in 
the y-sorted list
kbz                 low index of neighbors of each site in 
the z-sorted list
kex                 high index of neighbors of each site in 
the x-sorted list
key                 high index of neighbors of each site in 
the y-sorted list
kez                 high index of neighbors of each site in 
the z-sorted list
locx                pointer from x-sorted list into original 
interaction list
locy                pointer from y-sorted list into original 
interaction list
locz                pointer from z-sorted list into original 
interaction list
rgx                 pointer from original interaction list 
into x-sorted list
rgy                 pointer from original interaction list 
into y-sorted list
rgz                 pointer from original interaction list 
into z-sorted list

LINMIN              parameters for line search minimization

stpmin              minimum step length in current line 
search direction
stpmax              maximum step length in current line 
search direction
cappa               stringency of line search (0=tight < 
cappa < 1=loose)
angmax              maximum angle between search direction 
and -gradient
intmax              maximum number of inner iterations 
during line search

MATH                mathematical and geometrical constants

radian              conversion factor from radians to 
degrees
pi                  numerical value of the geometric 
constant
sqrtpi              numerical value of the square root of Pi
logten              numerical value of the natural log of 
ten
twosix              numerical value of the sixth root of two

MDSTUF              control of molecular dynamics trajectory

nfree               total number of degrees of freedom for a 
system
velsave             flag to save atomic velocity components 
to a file
uindsave            flag to save induced atomic dipoles to a 
file
integrate           type of molecular dynamics integration 
algorithm

MINIMA              general parameters for minimizations

fctmin              value below which function is deemed 
optimized
hguess              initial value for the H-matrix diagonal 
elements
maxiter             maximum number of iterations during 
optimization
nextiter            iteration number to use for the first 
iteration

MOLCUL              individual molecules within current 
system

molmass             molecular weight for each molecule in 
the system
totmass             total weight of all the molecules in the 
system
nmol                total number of separate molecules in 
the system
kmol                contiguous list of the atoms in each 
molecule
imol                first and last atom of each molecule in 
the list
molcule             number of the molecule to which each 
atom belongs

MOLDYN              velocity and acceleration on MD 
trajectory

v                   current velocity of each atom along the 
x,y,z-axes
a                   current acceleration of each atom along 
x,y,z-axes
aold                previous acceleration of each atom along 
x,y,z-axes

MOMENT              components of electric multipole moments

netchg              net electric charge for the total system
netdpl              dipole moment magnitude for the total 
system
netqdp              diagonal quadrupole (Qxx, Qyy, Qzz) for 
system
xdpl                dipole vector x-component in the global 
frame
ydpl                dipole vector y-component in the global 
frame
zdpl                dipole vector z-component in the global 
frame
xxqdp               quadrupole tensor xx-component in global 
frame
xyqdp               quadrupole tensor xy-component in global 
frame
xzqdp               quadrupole tensor xz-component in global 
frame
yxqdp               quadrupole tensor yx-component in global 
frame
yyqdp               quadrupole tensor yy-component in global 
frame
yzqdp               quadrupole tensor yz-component in global 
frame
zxqdp               quadrupole tensor zx-component in global 
frame
zyqdp               quadrupole tensor zy-component in global 
frame
zzqdp               quadrupole tensor zz-component in global 
frame

MPLPOT              specifics of atomic multipole functions

m2scale             factor by which 1-2 multipole 
interactions are scaled
m3scale             factor by which 1-3 multipole 
interactions are scaled
m4scale             factor by which 1-4 multipole 
interactions are scaled
m5scale             factor by which 1-5 multipole 
interactions are scaled

MPOLE               multipole components for current 
structure

maxpole             max components 
(monopole=1,dipole=4,quadrupole=13)
pole                multipole values for each site in the 
local frame
rpole               multipoles rotated to the global 
coordinate system
npole               total number of multipole sites in the 
system
ipole               number of the atom for each multipole 
site
polsiz              number of mutipole components at each 
multipole site
zaxis               number of the z-axis defining atom for 
each site
xaxis               number of the x-axis defining atom for 
each site
polaxe              local axis type for each multipole site

MUTANT              hybrid atoms for free energy 
perturbation

lambda              weighting of initial state in hybrid 
Hamiltonian
nhybrid             number of atoms mutated from initial to 
final state
ihybrid             atomic sites differing in initial and 
final state
type0               atom type of each atom in the initial 
state system
class0              atom class of each atom in the initial 
state system
type1               atom type of each atom in the final 
state system
class1              atom class of each atom in the final 
state system
alter               true if an atom is to be mutated, false 
otherwise

NUCLEO              parameters for nucleic acid structure

bkbone              phosphate backbone angles for each 
nucleotide
glyco               glycosidic torsional angle for each 
nucleotide
pucker              sugar pucker, either 2=2'-endo or 3=3'-
endo
dblhlx              flag to mark system as nucleic acid 
double helix
deoxy               flag to mark deoxyribose or ribose sugar 
units
hlxform             helix form (A, B or Z) of polynucleotide 
strands

OMEGA               dihedrals for torsional space 
computations

dihed               current value in radians of each 
dihedral angle
nomega              number of dihedral angles allowed to 
rotate
iomega              numbers of two atoms defining rotation 
axis
zline               line number in Z-matrix of each dihedral 
angle

OPBEND              out-of-plane bends in the current 
structure

kopb                force constant values for out-of-plane 
bending
nopbend             total number of out-of-plane bends in 
the system
iopb                bond angle numbers used in out-of-plane 
bending

OPDIST              out-of-plane distances in current 
structure

kopd                force constant values for out-of-plane 
distance
nopdist             total number of out-of-plane distances 
in the system
iopb                numbers of the atoms in each out-of-
plane distance

ORBITS              orbital energies for conjugated pisystem

q                   number of pi-electrons contributed by 
each atom
w                   ionization potential of each pisystem 
atom
em                  repulsion integral for each pisystem 
atom
nfill               number of filled pisystem molecular 
orbitals

OUTPUT              control of coordinate output file format

archive             logical flag to save structures in an 
archive
noversion           logical flag governing use of filename 
versions
overwrite           logical flag to overwrite intermediate 
files inplace
cyclesave           logical flag to mark use of numbered 
cycle files
coordtype           selects Cartesian, internal, rigid body 
or none

PATHS               parameters for Elber reaction path 
method

p0                  reactant Cartesian coordinates as 
variables
p1                  product Cartesian coordinates as 
variables
pmid                midpoint between the reactant and 
product
pvect               vector connecting the reactant and 
product
pstep               step per cycle along reactant-product 
vector
pzet                current projection on reactant-product 
vector
pnorm               length of the reactant-product vector
acoeff              transformation matrix 'A' from Elber 
paper
gc                  gradients of the path constraints

PDB                 definition of a Protein Data Bank 
structure

xpdb                x-coordinate of each atom stored in PDB 
format
ypdb                y-coordinate of each atom stored in PDB 
format
zpdb                z-coordinate of each atom stored in PDB 
format
npdb                number of atoms stored in Protein Data 
Bank format
resnum              number of the residue to which each atom 
belongs
npdb12              number of atoms directly bonded to each 
CONECT atom
ipdb12              atom numbers of atoms connected to each 
CONECT atom
pdblist             list of the Protein Data Bank atom 
number of each atom
pdbtyp              Protein Data Bank record type assigned 
to each atom
atmnam              Protein Data Bank atom name assigned to 
each atom
resnam              Protein Data Bank residue name assigned 
to each atom

PHIPSI              phi-psi-omega-chi angles for a protein

phi                 value of the phi angle for each amino 
acid residue
psi                 value of the psi angle for each amino 
acid residue
omega               value of the omega angle for each amino 
acid residue
chi                 values of the chi angles for each amino 
acid residue
chiral              chirality of each amino acid residue 
(1=L, -1=D)
disulf              residue joined to each residue via a 
disulfide link

PIORBS              conjugated system in the current 
structure

norbit              total number of pisystem orbitals in the 
system
iorbit              numbers of the atoms containing pisystem 
orbitals
reorbit             number of evaluations between orbital 
updates
piperp              atoms defining a normal plane to each 
orbital
npibond             total number of bonds affected by the 
pisystem
pibond              bond and piatom numbers for each 
pisystem bond
npitors             total number of torsions affected by the 
pisystem
pitors              torsion and pibond numbers for each 
pisystem torsion
listpi              atom list indicating whether each atom 
has an orbital

PISTUF              bonds and torsions in the current 
pisystem

bkpi                bond stretch force constants for pi-bond 
order of 1.0
blpi                ideal bond length values for a pi-bond 
order of 1.0
kslope              rate of force constant decrease with 
bond order decrease
lslope              rate of bond length increase with a bond 
order decrease
torspi              2-fold torsional energy barrier for pi-
bond order of 1.0

PME                 parameters for particle mesh Ewald 
summation

maxfft              maximum number of points along each FFT 
direction
maxorder            maximum order of the B-spline 
approximation
maxtable            maximum size of the FFT table array
maxgrid             maximum dimension of the PME charge grid 
array
bsmod1              B-spline moduli along the a-axis 
direction
bsmod2              B-spline moduli along the b-axis 
direction
bsmod3              B-spline moduli along the c-axis 
direction
table               intermediate array used by the FFT 
calculation
nfft1               number of grid points along the a-axis 
direction
nfft2               number of grid points along the b-axis 
direction
nfft3               number of grid points along the c-axis 
direction
bsorder             order of the PME B-spline approximation

POLAR               polarizabilities and induced dipole 
moments

polarity            dipole polarizability for each multipole 
site (Ang**3)
pdamp               value of polarizability damping factor 
for each site
uind                induced dipole components at each 
multipole site
uinp                induced dipoles in field used for energy 
interactions
npolar              total number of polarizable sites in the 
system

POLGRP              polarizable site group connectivity 
lists

maxp11              maximum number of atoms in a 
polarization group
maxp12              maximum number of atoms in groups 1-2 to 
an atom
maxp13              maximum number of atoms in groups 1-3 to 
an atom
maxp14              maximum number of atoms in groups 1-4 to 
an atom
np11                number of atoms in polarization group of 
each atom
ip11                atom numbers of atoms in same group as 
each atom
np12                number of atoms in groups 1-2 to each 
atom
ip12                atom numbers of atoms in groups 1-2 to 
each atom
np13                number of atoms in groups 1-3 to each 
atom
ip13                atom numbers of atoms in groups 1-3 to 
each atom
np14                number of atoms in groups 1-4 to each 
atom
ip14                atom numbers of atoms in groups 1-4 to 
each atom

POLPOT              specifics of polarization functional 
form

poleps              induced dipole convergence criterion 
(rms Debyes/atom)
polsor              induced dipole SOR convergence 
acceleration factor
pgamma              prefactor in exponential polarization 
damping term
p1scale             field intra-group scale factor for 
energy evaluations
p2scale             field 1-2 group scale factor for energy 
evaluations
p3scale             field 1-3 group scale factor for energy 
evaluations
p4scale             field 1-4 group scale factor for energy 
evaluations
d1scale             field intra-group scale factor for 
direct induced
d2scale             field 1-2 group scale factor for direct 
induced
d3scale             field 1-3 group scale factor for direct 
induced
d4scale             field 1-4 group scale factor for direct 
induced
u1scale             field intra-group scale factor for 
mutual induced
u2scale             field 1-2 group scale factor for mutual 
induced
u3scale             field 1-3 group scale factor for mutual 
induced
u4scale             field 1-4 group scale factor for mutual 
induced
polold              logical flag for scale factor instead of 
Thole damping
poltyp              type of polarization potential (direct 
or mutual)

POTENT              usage of each potential energy component

use_bond            logical flag governing use of bond 
stretch potential
use_angle           logical flag governing use of angle bend 
potential
use_strbnd          logical flag governing use of stretch-
bend potential
use_urey            logical flag governing use of Urey-
Bradley potential
use_angang          logical flag governing use of angle-
angle cross term
use_opbend          logical flag governing use of out-of-
plane bend term
use_opdist          logical flag governing use of out-of-
plane distance
use_improp          logical flag governing use of improper 
dihedral term
use_imptor          logical flag governing use of improper 
torsion term
use_tors            logical flag governing use of torsional 
potential
use_strtor          logical flag governing use of stretch-
torsion term
use_tortor          logical flag governing use of torsion-
torsion term
use_vdw             logical flag governing use of vdw der 
Waals potential
use_charge          logical flag governing use of charge-
charge potential
use_chgdpl          logical flag governing use of charge-
dipole potential
use_dipole          logical flag governing use of dipole-
dipole potential
use_mpole           logical flag governing use of multipole 
potential
use_polar           logical flag governing use of 
polarization term
use_rxnfld          logical flag governing use of reaction 
field term
use_solv            logical flag governing use of surface 
area solvation
use_gbsa            logical flag governing use of GB/SA 
solvation term
use_metal           logical flag governing use of ligand 
field term
use_geom            logical flag governing use of geometric 
restraints
use_extra           logical flag governing use of extra 
potential term
use_orbit           logical flag governing use of pisystem 
computation

PRECIS              values of machine precision tolerances

tiny                the smallest positive floating point 
value
small               the smallest relative floating point 
spacing
huge                the largest relative floating point 
spacing

REFER               storage of reference atomic coordinate 
set

xref                reference x-coordinate for each atom in 
the system
yref                reference y-coordinate for each atom in 
the system
zref                reference z-coordinate for each atom in 
the system
nref                total number of atoms in the reference 
system
reftyp              atom type for each atom in the reference 
system
n12ref              number of atoms bonded to each reference 
atom
i12ref              atom numbers of atoms 1-2 connected to 
each atom
refleng             length in characters of the reference 
filename
refltitle           length in characters of the reference 
title string
refnam              atom name for each atom in the reference 
system
reffile             base filename for the reference 
structure
reftitle            title used to describe the reference 
structure

RESDUE              standard biopolymer residue 
abbreviations

amino               three-letter abbreviations for amino 
acids types
nuclz               three-letter abbreviations for nucleic 
acids types
amino1              one-letter abbreviations for amino acids 
types
nuclz1              one-letter abbreviations for nucleic 
acids types

RGDDYN              velocities and momenta for rigid-body MD

vcm                 current translational velocity of each 
rigid-body
wcm                 current angular velocity of each rigid-
body
lm                  current angular momenta of each rigid-
body
linear              logical flag to mark group as linear or 
nonlinear

RIGID               rigid body coordinates for atom groups

xrb                 rigid body reference x-coordinate for 
each atom
yrb                 rigid body reference y-coordinate for 
each atom
zrb                 rigid body reference z-coordinate for 
each atom
rbc                 current rigid body coordinates for each 
atom group

RING                number and location of small ring 
structures

nring3              total number of 3-membered rings in the 
system
iring3              numbers of the atoms involved in each 3-
ring
nring4              total number of 4-membered rings in the 
system
iring4              numbers of the atoms involved in each 4-
ring
nring5              total number of 5-membered rings in the 
system
iring5              numbers of the atoms involved in each 5-
ring
nring6              total number of 6-membered rings in the 
system
iring6              numbers of the atoms involved in each 6-
ring

ROTATE              molecule partitions for rotation of a 
bond

nrot                total number of atoms moving when bond 
rotates
rot                 atom numbers of atoms moving when bond 
rotates
use_short           logical flag governing use of shortest 
atom list

RXNFLD              reaction field matrix elements and 
indices

b1
b2
ijk

RXNPOT              specifics of reaction field functional 
form

rfsize              radius of reaction field sphere centered 
at origin
rfbulkd             bulk dielectric constant of reaction 
field continuum
rfterms             number of terms to use in reaction field 
summation

SCALES              parameter scale factors for optimization

scale               multiplicative factor for each 
optimization parameter
set_scale           logical flag to show if scale factors 
have been set

SEQUEN              sequence information for a biopolymer

nseq                total number of residues in biopolymer 
sequences
nchain              number of separate biopolymer sequence 
chains
ichain              first and last residue in each 
biopolymer chain
seqtyp              residue type for each residue in the 
sequence
seq                 three-letter code for each residue in 
the sequence
chnnam              one-letter identifier for each sequence 
chain

SHAKE               definition of Shake/Rattle constraints

krat                ideal distance value for rattle 
constraint
nrat                number of rattle constraints to be 
applied
irat                atom numbers of atoms in a rattle 
constraint
ratimage            flag to use minimum image for rattle 
constraint
use_rattle          logical flag to set use of rattle 
contraints

SHUNT               polynomial switching function 
coefficients

off                 distance at which the potential energy 
goes to zero
off2                square of distance at which the 
potential goes to zero
cut                 distance at which switching of the 
potential begins
cut2                square of distance at which the 
switching begins
c0                  zeroth order coefficient of 
multiplicative switch
c1                  first order coefficient of 
multiplicative switch
c2                  second order coefficient of 
multiplicative switch
c3                  third order coefficient of 
multiplicative switch
c4                  fourth order coefficient of 
multiplicative switch
c5                  fifth order coefficient of 
multiplicative switch
f0                  zeroth order coefficient of additive 
switch function
f1                  first order coefficient of additive 
switch function
f2                  second order coefficient of additive 
switch function
f3                  third order coefficient of additive 
switch function
f4                  fourth order coefficient of additive 
switch function
f5                  fifth order coefficient of additive 
switch function
f6                  sixth order coefficient of additive 
switch function
f7                  seventh order coefficient of additive 
switch function

SIZES               parameter values to set array dimensions

"sizes.i" sets values for critical array dimensions used 
throughout the software; these parameters will fix the size 
of the largest systems that can be handled; values too large
for the computer's memory and/or swap space to accomodate 
will result in poor performance or outright failure

parameter:          maximum allowed number of:

maxatm              atoms in the molecular system
maxval              atoms directly bonded to an atom
maxgrp              user-defined groups of atoms
maxtyp              force field atom type definitions
maxclass            force field atom class definitions
maxkey              lines in the keyword file
maxrot              bonds for torsional rotation
maxvar              optimization variables (vector storage)
maxopt              optimization variables (matrix storage)
maxhess             off-diagonal Hessian elements
maxlight            sites for method of lights neighbors
maxvib              vibrational frequencies
maxgeo              distance geometry points
maxcell             unit cells in replicated crystal
maxring             3-, 4-, or 5-membered rings
maxfix              geometric restraints
maxbio              biopolymer atom definitions
maxres              residues in the macromolecule
maxamino            amino acid residue types
maxnuc              nucleic acid residue types
maxbnd              covalent bonds in molecular system
maxang              bond angles in molecular system
maxtors             torsional angles in molecular system
maxpi               atoms in conjugated pisystem
maxpib              covalent bonds involving pisystem
maxpit              torsional angles involving pisystem

SOLUTE              parameters for continuum solvation 
models

rsolv               atomic radius of each atom for continuum 
solvation
vsolv               atomic volume of each atom for continuum 
solvation
asolv               atomic solvation parameters 
(kcal/mole/Ang**2)
rborn               Born radius of each atom for GB/SA 
solvation
drb                 solvation derivatives with respect to 
Born radii
doffset             dielectric offset to continuum solvation 
atomic radii
p1                  single-atom scale factor for analytical 
Still GB/SA
p2                  1-2 interaction scale factor for 
analytical Still GB/SA
p3                  1-3 interaction scale factor for 
analytical Still GB/SA
p4                  nonbonded scale factor for analytical 
Still GB/SA
p5                  soft cutoff parameter for analytical 
Still GB/SA
gpol                polarization self-energy values for each 
atom
shct                overlap scaling factors for Hawkins-
Cramer-Truhlar GB/SA
wace                "omega" values for atom class pairs for 
use with ACE
s2ace               "sigma^2" values for atom class pairs 
for use with ACE
uace                "mu" values for atom class pairs for use 
with ACE
solvtyp             solvation model (ASP, SASA, ONION, 
STILL, HCT, ACE)

STODYN              frictional coefficients for SD 
trajectory

friction            global frictional coefficient for 
exposed particle
gamma               atomic frictional coefficients for each 
atom
use_sdarea          logical flag to use surface area 
friction scaling

STRBND              stretch-bends in the current structure

ksb                 force constant for stretch-bend terms
nstrbnd             total number of stretch-bend 
interactions
isb                 angle and bond numbers used in stretch-
bend

STRTOR              stretch-torsions in the current 
structure

kst                 1-, 2- and 3-fold stretch-torsion force 
constants
nstrtor             total number of stretch-torsion 
interactions
ist                 torsion and bond numbers used in 
stretch-torsion

SYNTRN              definition of synchronous transit path

t                   value of the path coordinate 
(0=reactant, 1=product)
pm                  path coordinate for extra point in 
quadratic transit
xmin1               reactant coordinates as array of 
optimization variables
xmin2               product coordinates as array of 
optimization variables
xm                  extra coordinate set for quadratic 
synchronous transit

TITLES              title for the current molecular system

ltitle              length in characters of the nonblank 
title string
title               title used to describe the current 
structure

TORPOT              specifics of torsional functional forms

idihunit            convert improper dihedral force to 
kcal/mole/deg**2
itorunit            convert improper torsion amplitudes to 
kcal/mole
torsunit            convert torsional parameter amplitudes 
to kcal/mole
storunit            convert stretch-torsion force to 
kcal/mole/Ang

TORS                torsional angles within the current 
structure

tors1               1-fold amplitude and phase for each 
torsional angle
tors2               2-fold amplitude and phase for each 
torsional angle
tors3               3-fold amplitude and phase for each 
torsional angle
tors4               4-fold amplitude and phase for each 
torsional angle
tors5               5-fold amplitude and phase for each 
torsional angle
tors6               6-fold amplitude and phase for each 
torsional angle
ntors               total number of torsional angles in the 
system
itors               numbers of the atoms in each torsional 
angle

TREE                potential smoothing & search tree levels

maxpss              maximum number of potential smoothing 
levels
etree               energy reference value at the top of the 
tree
ilevel              smoothing deformation value at each tree 
level
nlevel              number of levels of potential smoothing 
used

UNITS               physical constants and unit conversions

avogadro            Avogadro's number (N) in particles/mole
boltzmann           Boltzmann constant (kB) in 
g*Ang**2/ps**2/K/mole
gasconst            ideal gas constant (R) in kcal/mole/K
lightspd            speed of light in vacuum (c) in cm/ps
bohr                conversion from Bohrs to Angstroms
joule               conversion from calories to joules
evolt               conversion from Hartree to electron-
volts
hartree             conversion from Hartree to kcal/mole
electric            conversion from electron**2/Ang to 
kcal/mole
debye               conversion from electron-Ang to Debyes
prescon             conversion from kcal/mole/Ang**3 to Atm
convert             conversion from kcal to g*Ang**2/ps**2

UREY                Urey-Bradley interactions in the 
structure

uk                  Urey-Bradley force constants 
(kcal/mole/Ang**2)
ul                  ideal 1-3 distance values in Angstroms
nurey               total number of Urey-Bradley terms in 
the system
iury                numbers of the atoms in each Urey-
Bradley interaction

URYPOT              specifics of Urey-Bradley functional 
form

cury                cubic coefficient in Urey-Bradley 
potential
qury                quartic coefficient in Urey-Bradley 
potential
ureyunit            convert Urey-Bradley constant to 
kcal/mole/Ang**2

USAGE               atoms active during energy computation

nuse                number of active atoms used in energy 
calculation
use                 true if an atom is active, false if 
inactive

VDW                 van der Waals parameters for current 
structure

radmin              minimum energy distance for each atom 
class pair
epsilon             well depth parameter for each atom class 
pair
radmin4             minimum energy distance for 1-4 
interaction pairs
epsilon4            well depth parameter for 1-4 interaction 
pairs
radhbnd             minimum energy distance for hydrogen 
bonding pairs
epshbnd             well depth parameter for hydrogen 
bonding pairs
kred                value of reduction factor parameter for 
each atom
ired                attached atom from which reduction 
factor is applied
nvdw                total number van der Waals active sites 
in the system
ivdw                number of the atom for each van der 
Waals active site

VDWPOT              specifics of van der Waals functional 
form

abuck               value of "A" constant in Buckingham vdw 
potential
bbuck               value of "B" constant in Buckingham vdw 
potential
cbuck               value of "C" constant in Buckingham vdw 
potential
ghal                value of "gamma" in buffered 14-7 vdw 
potential
dhal                value of "delta" in buffered 14-7 vdw 
potential
v2scale             factor by which 1-2 vdw interactions are 
scaled
v3scale             factor by which 1-3 vdw interactions are 
scaled
v4scale             factor by which 1-4 vdw interactions are 
scaled
v5scale             factor by which 1-5 vdw interactions are 
scaled
igauss              coefficients of Gaussian fit to vdw 
potential
ngauss              number of Gaussians used in fit to vdw 
potential
vdwtyp              type of van der Waals potential energy 
function
radtyp              type of parameter (sigma or R-min) for 
atomic size
radsiz              atomic size provided as radius or 
diameter
radrule             combining rule for atomic size 
parameters
epsrule             combining rule for vdw well depth 
parameters
gausstyp            type of Gaussian fit to van der Waals 
potential

VIRIAL              components of the internal virial

virx                x-component of the total internal virial
viry                y-component of the total internal virial
virz                z-component of the total internal virial

WARP                parameters for potential surface 
smoothing

m2                  second moment of Gaussian representing 
each atom
deform              value of diffusional smoothing 
deformation parameter
difft               diffusion coefficient for torsional 
potential
diffv               diffusion coefficient for van der Waals 
potential
diffc               diffusion coefficient for charge-charge 
potential
use_deform          flag to use diffusion smoothed potential 
terms
use_gda             flag to use Straub's GDA instead of 
Scheraga's DEM

XTALS               crystal structures for parameter fitting

e0_lattice          ideal lattice energy for the current 
crystal
moment_0            ideal dipole moment for monomer from 
crystal
nxtal               number of crystal structures to be 
stored
nvary               number of potential parameters to 
optimize
ivary               index for the types of potential 
parameters
vary                atom numbers involved in potential 
parameters
iresid              crystal structure to which each residual 
refers
rsdtyp              experimental variable for each of the 
residuals
vartyp              type of potential parameter to be 
optimized

ZCLOSE              ring openings and closures for Z-matrix

nadd                number of added bonds between Z-matrix 
atoms
iadd                numbers of the atom pairs defining added 
bonds
ndel                number of bonds between Z-matrix bonds 
to delete
idel                numbers of the atom pairs defining 
deleted bonds

ZCOORD              Z-matrix internal coordinate definitions

zbond               bond length used to define each Z-matrix 
atom
zang                bond angle used to define each Z-matrix 
atom
ztors               angle or torsion used to define Z-matrix 
atom
iz                  defining atom numbers for each Z-matrix 
atom
 11.    Index of Function & Subroutine Calls

     This  section  contains  an  alphabetical  cross  index 
listing  of  the routines  called  by  each TINKER  program, 
subroutine and  function. Routines  not present in  the left 
hand column  do not make calls  to any other portion  of the 
TINKER package.

Routine    List of Source Code Units called by this Routine

ACTIVE     GETTEXT   UPCASE

ADDBASE    ADDBOND   FINDATM   JACOBI    NEWATM    OLDATM
           OVERLAP   PIALTER   PIMOVE    PITILT

ADDSIDE    ADDBASE   ADDBOND   FATAL     FINDATM   FREEUNIT
           JACOBI    NEWATM    OLDATM    OVERLAP   PIALTER
           PIMOVE    PITILT    PRTSEQ    VERSION

ALCHEMY    ENERGY    FINAL     FREEUNIT  GETTEXT   GETXYZ
           HATOM     HYBRID    INITIAL   MECHANIC  NUMERAL
           READXYZ   UPCASE    VERSION

ANALYSIS   BOUNDS    EANGANG3  EANGLE3   EBOND3    EBUCK3
           ECHARGE3  ECHGDPL3  EDIPOLE3  EGAUSS3   EGEOM3
           EHAL3     EIMPROP3  EIMPTOR3  ELJ3      EMETAL3
           EMM3HB3   EMPOLE3   EOPBEND3  EOPDIST3  ERXNFLD3
           ESOLV3    ESTRBND3  ESTRTOR3  ETORS3    EUREY3
           EXTRA3    PISCF     REPLICA

ANALYZE    ANALYZ4   ANALYZ6   ANALYZ8   ATOMYZE   ENRGYZE
           FINAL     FREEUNIT  GETXYZ    INITIAL   MECHANIC
           NEXTARG   PARAMYZE  PROPYZE   READXYZ   SUFFIX
           TRIMTEXT  UPCASE    VERSION

ANGLES     FATAL

ANNEAL     BEEMAN    FINAL     GETTEXT   GETXYZ    INITIAL
           MDINIT    MDREST    MECHANIC  NEXTARG   SDSTEP
           SHAKEUP   SIGMOID   UPCASE    VERLET

ARCHIVE    ACTIVE    BASEFILE  FINAL     FREEUNIT  GETTEXT
           INITIAL   NEXTARG   NUMERAL   PRTMSI    PRTXMOL
           PRTXYZ    READXYZ   SUFFIX    TRIMTEXT  UPCASE
           VERSION

ATTACH     SORT

BASEFILE   CONTROL   GETKEY    TRIMTEXT

BEEMAN     GRADIENT  MDSAVE    MDSTAT    PRESSURE  RATTLE
           RATTLE2   TEMPER

BETAI      BETACF    GAMMLN

BIGBLOCK   CELLATOM

BONDS      FATAL

BORN       SURFATOM

BSET       BMAX

BSSTEP     FATAL     MMID      PZEXTR

CALENDAR   IDATE     ITIME

CERROR     FATAL     TRIMTEXT

CFFTB      CFFTB1

CFFTB1     PASSB     PASSB2    PASSB3    PASSB4    PASSB5

CFFTF      CFFTF1

CFFTF1     PASSF     PASSF2    PASSF3    PASSF4    PASSF5

CFFTI      CFFTI1

CHKTREE    LOCALXYZ

CIRPLN     ANORM     DOT       VCROSS    VNORM

CLIMBER    ENERGY    GETREF    LOCALMIN  MAKEINT   MAKEXYZ

CLIMBRGD   ENERGY    LOCALRGD  RIGIDXYZ

CLIMBROT   ENERGY    LOCALROT  MAKEXYZ

CLIMBTOR   CHKTREE   ENERGY    GETREF    LOCALXYZ  MAKEINT
           MAKEXYZ

CLIMBXYZ   CHKTREE   ENERGY    GETREF    LOCALXYZ

CLUSTER    CUTOFFS   FATAL     GETNUMB   GETTEXT   SORT
           SORT3     UPCASE

COMMAND    GETARG    UPCASE

COMPRESS   CERROR    GETTOR

CONNECT    SORT

CONNOLLY   COMPRESS  CONTACT   NEIGHBOR  PLACE     SADDLES
           TORUS     VAM

CONTACT    ANORM     CERROR    PTINCY

CONTROL    GETTEXT   UPCASE

COORDS     GYRATE    RMSERROR

CORRELATE  FINAL     INITIAL   NEXTARG   PROPERTY  READBLK
           TRIMTEXT

CRYSTAL    BIGBLOCK  BOUNDS    FIELD     FINAL     FREEUNIT
           GETTEXT   GETXYZ    INITIAL   KATOM     LATTICE
           MOLECULE  NEXTARG   PRTXYZ    SYMMETRY  UNITCELL
           UPCASE    VERSION

CUTOFFS    GETTEXT   UPCASE

DEPTH      DOT       VCROSS    VNORM

DIAGQ      GETIME    SETIME

DIFFEQ     BSSTEP    DERIVS    GDASTAT

DIFFUSE    BASEFILE  FATAL     FIELD     FINAL     FREEUNIT
           GETWORD   INITIAL   KATOM     MOLECULE  NEXTARG
           READXYZ   SUFFIX    UNITCELL  VERSION

DISTGEOM   ACTIVE    ANGLES    ATTACH    BONDS     EMBED
           FATAL     FINAL     FREEUNIT  GEODESIC  GETIME
           GETTEXT   GETXYZ    GRAFIC    IMPOSE    INITIAL
           KCHIRAL   KGEOM     MAKEREF   NEXTARG   NUMERAL
           PRTXYZ    SETIME    TORSIONS  TRIFIX    UPCASE
           VERSION

DMDUMP     GRAFIC

DOCUMENT   FINAL     FREEUNIT  GETPRM    GETTEXT   GETWORD
           INITIAL   LOWCASE   NEXTARG   NEXTTEXT  PRTPRM
           SORT6     SORT7     SORT9     SUFFIX    TRIMTEXT
           UPCASE    VERSION

DSTMAT     GETIME    GETNUMB   GETTEXT   INVBETA   LOWCASE
           RANDOM    SETIME    SORT2     TRIFIX    UPCASE

DYNAMIC    BEEMAN    FINAL     GETXYZ    INITIAL   MDINIT
           MDREST    MECHANIC  NEXTARG   RGDSTEP   SDSTEP
           SHAKEUP   VERLET

EANGANG    GROUPS    IMAGE

EANGANG1   GROUPS    IMAGE

EANGANG2   EANGANG2A GROUP

EANGANG2A  IMAGE

EANGANG3   GROUPS    IMAGE

EANGLE     GROUPS    IMAGE

EANGLE1    GROUPS    IMAGE

EANGLE2    EANGLE2A  EANGLE2B  GROUPS

EANGLE2A   GROUPS    IMAGE

EANGLE2B   IMAGE

EANGLE3    GROUPS    IMAGE

EBOND      GROUPS    IMAGE

EBOND1     GROUPS    IMAGE

EBOND2     GROUPS    IMAGE

EBOND3     GROUPS    IMAGE

EBUCK      EBUCK0A   EBUCK0B

EBUCK0A    GROUPS    IMAGE     SWITCH

EBUCK0B    GROUPS    LIGHTS    SWITCH

EBUCK1     EBUCK1A   EBUCK1B

EBUCK1A    GROUPS    IMAGE     SWITCH

EBUCK1B    GROUPS    LIGHTS    SWITCH

EBUCK2     GROUPS    IMAGE     SWITCH

EBUCK3     EBUCK3A   EBUCK3B

EBUCK3A    GROUPS    IMAGE     SWITCH

EBUCK3B    GROUPS    LIGHTS    SWITCH

ECHARGE    ECHARGE0A ECHARGE0B ECHARGE0C ECHARGE0D

ECHARGE0A  GROUPS    IMAGE     SWITCH

ECHARGE0B  GROUPS    LIGHTS    SWITCH

ECHARGE0C  ERF       GROUPS

ECHARGE0D  EPME      ERFC      GROUPS    IMAGE     SWITCH

ECHARGE1   ECHARGE1A ECHARGE1B ECHARGE1C ECHARGE1D

ECHARGE1A  GROUPS    IMAGE     SWITCH

ECHARGE1B  GROUPS    LIGHTS    SWITCH

ECHARGE1C  ERF       GROUPS

ECHARGE1D  EPME1     ERFC      GROUPS    IMAGE     SWITCH

ECHARGE2   ECHARGE2A ECHARGE2B ECHARGE2C

ECHARGE2A  GROUPS    IMAGE     SWITCH

ECHARGE2B  ERF       GROUPS

ECHARGE2C  ERFC      GROUPS    IMAGE

ECHARGE3   ECHARGE3A ECHARGE3B ECHARGE3C ECHARGE3D

ECHARGE3A  GROUPS    IMAGE     SWITCH

ECHARGE3B  GROUPS    LIGHTS    SWITCH

ECHARGE3C  ERF       GROUPS

ECHARGE3D  EPME3     ERFC      GROUPS    IMAGE     SWITCH

ECHGDPL    GROUPS    IMAGE     SWITCH

ECHGDPL1   GROUPS    IMAGE     SWITCH

ECHGDPL2   GROUPS    IMAGE     SWITCH

ECHGDPL3   GROUPS    IMAGE     SWITCH

EDIPOLE    GROUPS    IMAGE     SWITCH

EDIPOLE1   GROUPS    IMAGE     SWITCH

EDIPOLE2   GROUPS    IMAGE     SWITCH

EDIPOLE3   GROUPS    IMAGE     SWITCH

EGAUSS     GROUPS    SWITCH

EGAUSS1    GROUPS    SWITCH

EGAUSS2    GROUPS    SWITCH

EGAUSS3    GROUPS    SWITCH

EGBSA0A    GROUPS    SWITCH

EGBSA0B    ERF       GROUPS

EGBSA1A    GROUPS    SWITCH

EGBSA1B    ERF       GROUPS

EGBSA2A    SWITCH

EGBSA2B    ERF

EGBSA3A    GROUPS    SWITCH

EGBSA3B    ERF       GROUPS

EGEOM      GROUPS    IMAGE

EGEOM1     GROUPS    IMAGE

EGEOM2     GROUPS    IMAGE

EGEOM3     GROUPS    IMAGE

EHAL       EHAL0A    EHAL0B

EHAL0A     GROUPS    IMAGE     SWITCH

EHAL0B     GROUPS    LIGHTS    SWITCH

EHAL1      EHAL1A    EHAL1B

EHAL1A     GROUPS    IMAGE     SWITCH

EHAL1B     GROUPS    LIGHTS    SWITCH

EHAL2      GROUPS    IMAGE     SWITCH

EHAL3      EHAL3A    EHAL3B

EHAL3A     GROUPS    IMAGE     SWITCH

EHAL3B     GROUPS    LIGHTS    SWITCH

EIGEN      GETIME    POWER     SETIME

EIGENRGD   DIAGQ     HESSRGD

EIGENROT   DIAGQ     HESSROT

EIGENROT   DIAGQ     HESSROT

EIGENTOR   DIAGQ     HESSROT

EIGENXYZ   DIAGQ     HESSIAN

EIMPROP    GROUPS    IMAGE

EIMPROP1   GROUPS    IMAGE

EIMPROP2   GROUPS    IMAGE

EIMPROP3   GROUPS    IMAGE

EIMPTOR    GROUPS    IMAGE

EIMPTOR1   GROUPS    IMAGE

EIMPTOR2   GROUPS    IMAGE

EIMPTOR3   GROUPS    IMAGE

ELJ        ELJ0A     ELJ0B

ELJ0A      GROUPS    IMAGE     SWITCH

ELJ0B      GROUPS    LIGHTS    SWITCH

ELJ1       ELJ1A     ELJ1B

ELJ1A      GROUPS    IMAGE     SWITCH

ELJ1B      GROUPS    LIGHTS    SWITCH

ELJ2       GROUPS    IMAGE     SWITCH

ELJ3       ELJ3A     ELJ3B

ELJ3A      GROUPS    IMAGE     SWITCH

ELJ3B      GROUPS    LIGHTS    SWITCH

EMBED      BNDERR    CHIRER    CHKSIZE   COORDS    DMDUMP
           DSTMAT    EIGEN     EXPLORE   FRACDIST  FREEUNIT
           GETIME    GYRATE    IMPOSE    LOCERR    MAJORIZE
           METRIC    NUMERAL   PRTXYZ    REFINE    RMSERROR
           SETIME    TORSER    VDWERR

EMETAL     FATAL

EMETAL1    FATAL

EMETAL3    EMETAL

EMM3HB     EMM3HB0A  EMM3HB0B

EMM3HB0A   GROUPS    IMAGE     SWITCH

EMM3HB0B   GROUPS    LIGHTS    SWITCH

EMM3HB1    EMM3HB1A  EMM3HB1B

EMM3HB1A   GROUPS    IMAGE     SWITCH

EMM3HB1B   GROUPS    LIGHTS    SWITCH

EMM3HB2    GROUPS    IMAGE     SWITCH

EMM3HB3    EMM3HB3A  EMM3HB3B

EMM3HB3A   GROUPS    IMAGE     SWITCH

EMM3HB3B   GROUPS    LIGHTS    SWITCH

EMPOLE     EMPOLE0A  EMPOLE0B

EMPOLE0A   GROUPS    IMAGE     INDUCE    ROTMAT    ROTPOLE
           SWITCH

EMPOLE0B   EREAL     ERECIP    INDUCE    ROTMAT    ROTPOLE

EMPOLE1    EMPOLE1A  EMPOLE1B

EMPOLE1A   GROUPS    IMAGE     INDUCE    ROTMAT    ROTPOLE
           SWITCH    TORQUE    TORQUE1

EMPOLE1B   EREAL1    ERECIP1   INDUCE    ROTMAT    ROTPOLE
           TORQUE

EMPOLE2    EMPOLE2A

EMPOLE2A   GROUPS    IMAGE     ROTMAT    ROTPOLE   SWITCH
           TORQUE

EMPOLE3    EMPOLE3A  EMPOLE3B

EMPOLE3A   GROUPS    IMAGE     INDUCE    ROTMAT    ROTPOLE
           SWITCH

EMPOLE3B   EREAL3    ERECIP3   INDUCE    ROTMAT    ROTPOLE

ENERGY     BOUNDS    EANGANG   EANGLE    EBOND     EBUCK
           ECHARGE   ECHGDPL   EDIPOLE   EGAUSS    EGEOM
           EHAL      EIMPROP   EIMPTOR   ELJ       EMETAL
           EMM3HB    EMPOLE    EOPBEND   EOPDIST   ERXNFLD
           ESOLV     ESTRBND   ESTRTOR   ETORS     EUREY
           EXTRA     PISCF     REPLICA

ENRGYZE    ANALYSIS

EOPBEND    GROUPS    IMAGE

EOPBEND1   GROUPS    IMAGE

EOPBEND2   EOPBEND2A GROUPS

EOPBEND2A  IMAGE

EOPBEND3   GROUPS    IMAGE

EOPDIST    GROUPS    IMAGE

EOPDIST1   GROUPS    IMAGE

EOPDIST2   GROUPS    IMAGE

EOPDIST3   GROUPS    IMAGE

EPME       BSPLINE   FFTFRONT

EPME1      BSPLINE1  FFTBACK   FFTFRONT

EPME3      BSPLINE   FFTFRONT

EPUCLC     ANORM

EREAL      ERFC      IMAGE     SWITCH

EREAL1     ERFC      IMAGE     SWITCH    TORQUE    TORQUE1

EREAL3     ERFC      IMAGE     SWITCH

ERECIP1    TORQUE

ERF        ERFCORE

ERFC       ERFCORE

ERFIK      D1D2      RFINDEX

ERFINV     ERF       FATAL

ERXNFLD    ERFIK     IJK_PT    ROTMAT    ROTPOLE   SWITCH

ERXNFLD3   ERFIK     IJK_PT    ROTMAT    ROTPOLE   SWITCH

ESOLV      BORN      EGBSA0A   EGBSA0B   SURFACE

ESOLV1     BORN      BORN1     EGBSA1A   EGBSA1B   SURFACE

ESOLV2     EGBSA2A   EGBSA2B

ESOLV3     BORN      EGBSA3A   EGBSA3B   SURFACE

ESTRBND    GROUPS    IMAGE

ESTRBND1   GROUPS    IMAGE

ESTRBND2   GROUPS    IMAGE

ESTRBND3   GROUPS    IMAGE

ESTRTOR    GROUPS    IMAGE

ESTRTOR1   GROUPS    IMAGE

ESTRTOR2   GROUPS    IMAGE

ESTRTOR3   GROUPS    IMAGE

ETORS      GROUPS    IMAGE

ETORS1     GROUPS    IMAGE

ETORS2     GROUPS    IMAGE

ETORS3     GROUPS    IMAGE

EUREY      GROUPS    IMAGE

EUREY1     GROUPS    IMAGE

EUREY2     GROUPS    IMAGE

EUREY3     GROUPS    IMAGE

EWALDCOF   ERFC

EXPLORE    INITERR   MIDERR    SIGMOID   TOTERR

FFTBACK    CFFTB

FFTFRONT   CFFTF

FFTSETUP   CFFTI

FIELD      GETPRM    PRMKEY

FRACDIST   DIST2     TRIMTEXT

FREEUNIT   FATAL

GDA        DIFFEQ    FINAL     FREEUNIT  GDASTAT   GETTEXT
           GETXYZ    INITIAL   MECHANIC  NEXTARG   NUMERAL
           PRTXYZ    RANDOM    TNCG      UPCASE    VERSION

GDA1       GRADIENT  HESSIAN

GDA2       GRADIENT

GDA3       HESSIAN

GDASTAT    ENERGY    GYRATE    WRITEOUT

GEODESIC   MINPATH   SORT3

GETBASE    PDBATM

GETIME     CLOCK

GETINT     BASEFILE  CHKXYZ    CONNECT   FATAL     FREEUNIT
           MAKEXYZ   NEXTARG   READINT   SUFFIX    VERSION

GETKEY     FATAL     FREEUNIT  GETTEXT   SUFFIX    TRIMTEXT
           UPCASE

GETMOL2    BASEFILE  FREEUNIT  NEXTARG   READMOL2  SUFFIX
           VERSION

GETNUCH    PDBATM

GETNUMB    TRIMTEXT

GETPDB     BASEFILE  FREEUNIT  NEXTARG   READPDB   SUFFIX
           VERSION

GETPRB     DIST2     DOT       GETTOR    VCROSS

GETPRM     FREEUNIT  GETTEXT   INITPRM   NEXTARG   READPRM
           SUFFIX    UPCASE    VERSION

GETPROH    PDBATM

GETSEQ     GETWORD   TRIMTEXT  UPCASE

GETSEQN    GETTEXT   GETWORD   TRIMTEXT  UPCASE

GETSIDE    PDBATM

GETTOR     DIST2

GETXYZ     BASEFILE  FATAL     FREEUNIT  NEXTARG   READXYZ
           SUFFIX    VERSION

GRADIENT   BOUNDS    EANGANG1  EANGLE1   EBOND1    EBUCK1
           ECHARGE1  ECHGDPL1  EDIPOLE1  EGAUSS1   EGEOM1
           EHAL1     EIMPROP1  EIMPTOR1  ELJ1      EMETAL1
           EMM3HB1   EMPOLE1   EOPBEND1  EOPDIST1  ERXNFLD1
           ESOLV1    ESTRBND1  ESTRTOR1  ETORS1    EUREY1
           EXTRA1    PISCF     REPLICA

GRADRGD    GRADIENT

GRADROT    GRADIENT  ROTLIST

HANGLE     NUMERAL

HBOND      NUMERAL

HDIPOLE    NUMERAL

HESSIAN    BORN      BOUNDS    EANGANG2  EANGLE2   EBOND2
           EBUCK2    ECHARGE2  ECHGDPL2  EDIPOLE2  EGAUSS2
           EGEOM2    EHAL2     EIMPROP2  EIMPTOR2  ELJ2
           EMETAL2   EMM3HB2   EMPOLE2   EOPBEND2  EOPDIST2
           ERXNFLD2  ESOLV2    ESTRBND2  ESTRTOR2  ETORS2
           EUREY2    EXTRA2    FATAL     INDUCE    PISCF
           REPLICA

HESSRGD    GRADRGD   RIGIDXYZ

HESSROT    GRADROT   MAKEXYZ

HIMPTOR    NUMERAL

HSTRTOR    NUMERAL

HTORS      NUMERAL

HYBRID     HANGLE    HATOM     HBOND     HCHARGE   HDIPOLE
           HIMPTOR   HSTRBND   HSTRTOR   HTORS     HVDW

IMPOSE     CENTER    QUATFIT   RMSFIT

INDUCE     INDUCE0A  INDUCE0B

INDUCE0A   FATAL     GROUPS    IMAGE     PRTERR    SWITCH

INDUCE0B   FATAL     PRTERR    UDIRECT1  UDIRECT2  UMUTUAL1
           UMUTUAL2

INEDGE     CERROR

INERTIA    JACOBI

INITERR    LOCERR    TORSER

INITIAL    COMMAND   INITRES   PRECISE   PROMO

INITROT    FATAL     NEXTARG   ROTCHECK  ROTLIST

INTEDIT    FIELD     FINAL     FREEUNIT  GEOMETRY  GETINT
           GETWORD   INITIAL   MAKEXYZ   NUMBER    PRTINT
           TRIMTEXT  UPCASE    VERSION   ZHELP     ZVALUE

INTXYZ     FINAL     FREEUNIT  GETINT    INITIAL   PRTXYZ
           VERSION

INVBETA    BETAI     GAMMLN

INVERT     FATAL

IPEDGE     CERROR

KANGANG    GETTEXT   UPCASE

KANGLE     GETTEXT   NUMERAL   UPCASE

KATOM      GETNUMB   GETSTRING GETTEXT   UPCASE

KBOND      GETTEXT   KENEG     NUMERAL   UPCASE

KCHARGE    GETTEXT   UPCASE

KDIPOLE    GETTEXT   NUMERAL   UPCASE

KENEG      GETTEXT   NUMERAL   UPCASE

KEWALD     EWALDCOF  FATAL     FFTSETUP  GETTEXT   MODULI
           UPCASE

KGEOM      FATAL     GEOMETRY  GETTEXT   UPCASE

KIMPROP    GETTEXT   NUMERAL   UPCASE

KIMPTOR    GETTEXT   NUMERAL   TORPHASE  UPCASE

KMPOLE     GETTEXT   NUMBER    NUMERAL   RANDOM    SORT3
           UPCASE

KOPBEND    GETTEXT   NUMBER    NUMERAL   UPCASE

KOPDIST    GETTEXT   NUMERAL   UPCASE

KORBIT     GETTEXT   NUMERAL   UPCASE

KPOLAR     GETTEXT   POLARGRP  UPCASE

KSOLV      GETTEXT   GETWORD   KANGLE    KBOND     UPCASE

KSTRBND    GETTEXT   UPCASE

KSTRTOR    GETTEXT   NUMERAL   UPCASE

KTORS      GETTEXT   NUMERAL   TORPHASE  UPCASE

KUREY      GETTEXT   NUMERAL   UPCASE

KVDW       GETTEXT   NUMBER    NUMERAL   UPCASE

LBFGS      COMMENT'  GETTEXT   SEARCH    UPCASE    WRITEOUT

LIGASE     FINDATM

LIGHTS     FATAL     SORT2     SORT5

LMSTEP     PRECISE   QRSOLVE

LOCALMIN   GRADIENT  TNCG

LOCALRGD   OCVM

LOCALROT   OCVM

LOCALXYZ   TNCG

MAJORIZE   GETIME    GYRATE    RMSERROR  SETIME

MAKEINT    ADJACENT  FATAL     GEOMETRY  GETTEXT   UPCASE

MAKEPDB    ATTACH    FREEUNIT  GETBASE   GETNUCH   GETPROH
           GETSIDE   NUMERAL   PDBATM    READSEQ   VERSION

MAKEXYZ    XYZATM

MAPCHECK   FREEUNIT  NUMERAL   PRTXYZ    VERSION

MAXWELL    ERFINV    RANDOM

MDINIT     FREEUNIT  GETTEXT   GETWORD   GRADIENT  GRPLINE
           LATTICE   MAXWELL   MDREST    NUMERAL   RANVEC
           READDYN   UPCASE    VERSION

MDREST     INVERT

MDSAVE     FATAL     FREEUNIT  NUMERAL   OPENEND   PRTDYN
           PRTXYZ    SUFFIX    VERSION

MEASFN     CERROR    TRIPLE    VCROSS    VECANG    VNORM

MEASFP     CERROR    DOT       VCROSS    VECANG    VNORM

MEASFS     CERROR    DOT       VECANG    VNORM

MEASPM     VCROSS

MECHANIC   ACTIVE    ANGLES    ATTACH    BONDS     CLUSTER
           CUTOFFS   FATAL     FIELD     KANGANG   KANGLE
           KATOM     KBOND     KCHARGE   KDIPOLE   KEWALD
           KGEOM     KIMPROP   KIMPTOR   KMETAL    KMPOLE
           KOPBEND   KOPDIST   KORBIT    KPOLAR    KSOLV
           KSTRBND   KSTRTOR   KTORS     KUREY     KVDW
           LATTICE   MOLECULE  MUTATE    ORBITAL   POLYMER
           RINGS     SMOOTH    TORSIONS  UNITCELL

MERGE      FATAL     GETREF

MIDERR     BNDERR    CHIRER    LOCERR    TORSER

MINIMIZ1   GRADIENT

MINIMIZE   FINAL     FREEUNIT  GETXYZ    GRADIENT  INITIAL
           LBFGS     MECHANIC  NEXTARG   PRTXYZ    VERSION

MINIROT    FINAL     FREEUNIT  GETINT    GRADROT   INITIAL
           INITROT   LBFGS     MECHANIC  NEXTARG   PRTINT
           VERSION

MINIROT1   GRADROT   MAKEXYZ

MINRIGID   FINAL     FREEUNIT  GETXYZ    GRADRGD   INITIAL
           LBFGS     MECHANIC  NEXTARG   ORIENT    PRTXYZ
           VERSION

MINRIGID1  GRADRGD   RIGIDXYZ  XYZRIGID

MMID       DERIVS

MODECART   CLIMBXYZ  EIGENXYZ  GETREF    IMPOSE    MAKEREF

MODEROT    CLIMBROT  EIGENROT  MAKEXYZ

MODESRCH   CLIMBER   EIGENROT  MAKEINT   MAKEREF   MAPCHECK

MODETORS   CLIMBTOR  EIGENTOR  GETREF    IMPOSE    MAKEINT
           MAKEREF

MODULI     BSPLINE   DFTMOD

MOLECULE   SORT      SORT3

MOLUIND    UFIELD

MOMENTS    INDUCE    JACOBI    ROTMAT    ROTPOLE

MUTATE     GETTEXT   UPCASE

NEIGHBOR   CERROR    DIST2

NEWATM     ADDBOND   XYZATM

NEWTON     FINAL     FREEUNIT  GETTEXT   GETXYZ    GRADIENT
           INITIAL   MECHANIC  NEXTARG   PRTXYZ    TNCG
           UPCASE    VERSION

NEWTON1    GRADIENT

NEWTON2    HESSIAN

NEWTROT    FINAL     FREEUNIT  GETINT    GETTEXT   GRADROT
           INITIAL   INITROT   MECHANIC  NEXTARG   PRTINT
           TNCG      UPCASE    VERSION

NEWTROT1   GRADROT   MAKEXYZ

NEWTROT2   HESSROT   MAKEXYZ

NORMAL     RANDOM

NUCBASE    OCVM      ORIENT    POTOFF    ZATOM

NUCCHAIN   NUCBASE   OCVM      ORIENT    ZATOM

NUCLEIC    BASEFILE  CONNECT   DELETE    FIELD     FREEUNIT
           GETKEY    GETSEQN   INITIAL   MAKEINT   MAKEXYZ
           MOLECULE  NEXTARG   NUCCHAIN  PRTINT    PRTSEQ
           PRTXYZ    TRIMTEXT  VERSION   WATSON

NUMBER     TRIMTEXT

OCVM       GETTEXT   PRECISE   UPCASE    WRITEOUT

OLDATM     ADDBOND   FATAL

OPTIMIZ1   GRADIENT

OPTIMIZE   FATAL     FINAL     FREEUNIT  GETXYZ    GRADIENT
           INITIAL   MECHANIC  NEXTARG   OCVM      PRTXYZ
           VERSION

OPTIROT    FATAL     FINAL     FREEUNIT  GETINT    GRADROT
           INITIAL   INITROT   MECHANIC  NEXTARG   OCVM
           PRTINT    VERSION

OPTIROT1   GRADROT   MAKEXYZ

OPTRIGID   FATAL     FINAL     FREEUNIT  GETXYZ    GRADRGD
           INITIAL   MECHANIC  NEXTARG   OCVM      ORIENT
           PRTXYZ    VERSION

OPTRIGID1  GRADRGD   RIGIDXYZ  XYZRIGID

ORBITAL    FATAL     GETTEXT   PIPLANE   UPCASE

ORIENT     XYZRIGID

OVERLAP    SLATER

PATH       FINAL     GETXYZ    IMPOSE    INITIAL   INVERT
           LBFGS     MECHANIC  NEXTARG   ORTHOG    POTNRG
           WRITEOUT

PATH1      POTNRG

PATHPNT    OCVM

PATHSCAN   PATHPNT   SADDLE1   TANGENT

PATHVAL    IMPOSE

PDBXYZ     CHKXYZ    DELETE    FIELD     FINAL     FREEUNIT
           GETNUMB   GETPDB    INITIAL   LIGASE    PRTXYZ
           RIBOSOME  SORT      UPCASE    VERSION

PIPLANE    FATAL

PISCF      NEWATM

PITILT     OLDATM

PLACE      CERROR    DIST2     GETPRB    GETTOR    INEDGE

POLARGRP   SORT      SORT8

POLARIZE   FATAL     GETXYZ    INITIAL   JACOBI    MECHANIC
           MOLUIND

POLYMER    FATAL     GETTEXT   IMAGE     UPCASE

POTNRG     GRADIENT

POWER      RANDOM

PRECOND    CHOLESKY  COLUMN

PRESSURE   LATTICE

PRMKEY     GETTEXT   GETWORD   POTOFF    UPCASE

PROCHAIN   GETTEXT   PROSIDE   UPCASE    ZATOM

PROJCT     DOT

PROPYZE    GYRATE    INERTIA   MOMENTS

PROSIDE    FREEUNIT  PRTINT    PRTXYZ    VERSION   ZATOM

PROTEIN    BASEFILE  CHKXYZ    CONNECT   DELETE    FIELD
           FINAL     FREEUNIT  GETKEY    GETSEQ    INITIAL
           MAKEINT   MAKEXYZ   NEXTARG   PROCHAIN  PRTINT
           PRTSEQ    PRTXYZ    TRIMTEXT  VERSION

PRTDYN     ZATOM

PRTERR     ZATOM

PRTINT     VERSION

PRTMOL2    NUMBER    VERSION

PRTMSI     VERSION

PRTPDB     VERSION

PRTPRM     NUMBER

PRTSEQ     VERSION

PRTXMOL    VERSION

PRTXYZ     VERSION

PSS        ACTIVE    FINAL     GETTEXT   GETXYZ    IMPOSE
           INITIAL   INITROT   LOCALXYZ  MAKEINT   MAKEREF
           MECHANIC  MODECART  MODETORS  NEXTARG   PSSWRITE
           SIGMOID   UPCASE

PSS1       GRADIENT

PSS2       HESSIAN

PSSRGD1    GRADRGD   RIGIDXYZ

PSSRIGID   FINAL     FREEUNIT  GETTEXT   GETXYZ    IMPOSE
           INITIAL   MAKEREF   MECHANIC  NEXTARG   NUMERAL
           OCVM      ORIENT    PRTXYZ    RGDSRCH   RIGIDXYZ
           SIGMOID   UPCASE    VERSION

PSSROT     FINAL     FREEUNIT  GETINT    GETTEXT   IMPOSE
           INITIAL   INITROT   MAKEREF   MAKEXYZ   MECHANIC
           MODEROT   NEXTARG   NUMERAL   OCVM      PRTXYZ
           UPCASE    VERSION

PSSROT1    GRADROT   MAKEXYZ

PSSWRITE   FREEUNIT  NUMERAL   PRTXYZ    VERSION

PTINCY     DOT       EPUCLC    PROJCT    ROTANG

QUATFIT    JACOBI

RADIAL     FINAL     FREEUNIT  GETWORD   GETXYZ    IMAGE
           INITIAL   LATTICE   MOLECULE  NUMERAL   READXYZ
           TRIMTEXT  UNITCELL  VERSION

RANDOM     CALENDAR  GETTEXT   UPCASE

RANVEC     RANDOM

RATTLE     FATAL     IMAGE     PRTERR

RATTLE2    FATAL     IMAGE     PRTERR

READBLK    FATAL     FREEUNIT  GETWORD   NUMERAL

READDYN    FATAL     VERSION

READINT    FATAL     GETTEXT   GETWORD   NEXTTEXT  TRIMTEXT
           VERSION

READMOL2   FATAL     GETTEXT   GETWORD   SORT      TRIMTEXT
           UPCASE    VERSION

READPDB    FATAL     FIXPDB    GETTEXT   TRIMTEXT  UPCASE
           VERSION

READPRM    FATAL     GETNUMB   GETSTRING GETTEXT   GETWORD
           NUMERAL   PRMKEY    TORPHASE  TRIMTEXT  UPCASE

READSEQ    FATAL     GETNUMB   GETTEXT   GETWORD   TRIMTEXT
           VERSION

READXYZ    CHKXYZ    FATAL     GETTEXT   GETWORD   NEXTTEXT
           SORT      TRIMTEXT  VERSION

REFINE     LBFGS

REPLICA    FATAL

RGDSRCH    CLIMBRGD  EIGENRGD  RIGIDXYZ

RGDSTEP    GRADIENT  LINBODY   MDSAVE    MDSTAT    NEWCRD
           PRESSURE  REGBODY   ROTRGD    TEMPER

RIBOSOME   ADDBOND   ADDSIDE   FATAL     FINDATM   FREEUNIT
           NEWATM    OLDATM    PRTSEQ    VERSION

RINGS      ANGLES    BONDS     FATAL     TORSIONS

RMSERROR   TRIMTEXT

ROTANG     DOT       VCROSS

ROTCHECK   ROTLIST

ROTLIST    FATAL

SADDLE     COMMENT'  FATAL     FINAL     FREEUNIT  GETTEXT
           GETXYZ    IMPOSE    INITIAL   MAKEINT   MAKEXYZ
           MECHANIC  NEXTARG   PATHPNT   PATHSCAN  PATHVAL
           PRTXYZ    READXYZ   SADDLE1   SEARCH    TANGENT
           UPCASE    VERSION

SADDLE1    GRADIENT

SADDLES    CERROR    IPEDGE    TRIPLE

SCAN       ACTIVE    FINAL     FREEUNIT  GETXYZ    INITIAL
           INITROT   LOCALMIN  MAKEINT   MAPCHECK  MECHANIC
           MODESRCH  NEXTARG   NUMERAL   READXYZ   VERSION

SCAN1      GRADIENT

SCAN2      HESSIAN

SDAREA     SURFATOM

SDSTEP     GRADIENT  MDSAVE    MDSTAT    RATTLE    RATTLE2
           SDTERM

SDTERM     NORMAL    SDAREA

SETIME     CLOCK

SHAKEUP    GETNUMB   GETTEXT   GETWORD   UPCASE

SLATER     ASET      BSET      CJKM      POLYP

SMOOTH     GETTEXT   NEXTARG   UPCASE

SNIFFER    FINAL     FREEUNIT  GETREF    GETXYZ    GRADIENT
           INITIAL   MAKEREF   MECHANIC  NEXTARG   PRTXYZ
           SNIFFER1  VERSION   WRITEOUT

SNIFFER1   GRADIENT

SOAK       DELETE    FREEUNIT  IMAGE     LATTICE   MAKEREF
           MERGE     MOLECULE  READXYZ   SUFFIX    UNITCELL
           VERSION

SPACEFILL  ACTIVE    CONNOLLY  FIELD     FINAL     FREEUNIT
           GETTEXT   GETXYZ    INITIAL   KATOM     KVDW
           NEXTARG   READXYZ   SUFFIX    UPCASE    VERSION

SPECTRUM   BASEFILE  FREEUNIT  INITIAL   NEXTARG   SUFFIX
           VERSION

SQUARE     GETTEXT   LMSTEP    PRECISE   QRFACT    RSDVALUE
           TRUST     UPCASE    WRITEOUT

SUFFIX     TRIMTEXT

SUPERPOSE  FIELD     FINAL     FREEUNIT  GETTEXT   GETXYZ
           IMPOSE    INITIAL   KATOM     NEXTARG   PRTXYZ
           READXYZ   SUFFIX    TRIMTEXT  UPCASE    VERSION

SURFACE    FATAL     SORT2

SURFATOM   FATAL     SORT2

SWITCH     REPLICA

SYBYLXYZ   FINAL     FREEUNIT  GETMOL2   INITIAL   PRTXYZ
           VERSION

SYMMETRY   CELLATOM

TANGENT    PATHPNT   SADDLE1

TEMPER     MAXWELL   RANDOM    RANVEC

TESTGRAD   ENERGY    FINAL     GETTEXT   GETXYZ    GRADIENT
           INITIAL   MECHANIC  NEXTARG   UPCASE

TESTHESS   FINAL     FREEUNIT  GETTEXT   GETXYZ    GRADIENT
           HESSIAN   INITIAL   MECHANIC  NEXTARG   NUMGRAD
           UPCASE    VERSION

TESTLIGHT  EBUCK     EBUCK1    ECHARGE   ECHARGE1  EGAUSS
           EGAUSS1   EHAL      EHAL1     ELJ       ELJ1
           EMM3HB    EMM3HB1   FINAL     GETIME    GETXYZ
           INITIAL   LIGHTS    MECHANIC  NEXTARG   SETIME

TESTROT    ENERGY    FINAL     GETINT    GRADROT   INITIAL
           INITROT   MAKEXYZ   MECHANIC  NEXTARG

TIMER      ENERGY    FINAL     GETIME    GETTEXT   GETXYZ
           GRADIENT  HESSIAN   INITIAL   MECHANIC  NEXTARG
           SETIME    UPCASE

TIMEROT    ENERGY    FINAL     GETIME    GETINT    GETTEXT
           GRADROT   HESSROT   INITIAL   INITROT   MECHANIC
           NEXTARG   SETIME    UPCASE

TNCG       GETTEXT   HMATRIX   PISCF     SEARCH    TNSOLVE
           UPCASE    WRITEOUT

TNSOLVE    PRECOND

TORSIONS   FATAL

TORUS      CERROR    GETTOR

TOTERR     BNDERR    CHIRER    LOCERR    TORSER    VDWERR

TRIANGLE   FATAL

TRIPLE     DOT       VCROSS

TRUST      PRECISE   RSDVALUE

UDIRECT2   ERFC      IMAGE     SWITCH

UMUTUAL2   ERFC      IMAGE     SWITCH

UNITCELL   FATAL     GETTEXT   GETWORD   UPCASE

VAM        CERROR    CIRPLN    DEPTH     DIST2     DOT
           GENDOT    MEASFN    MEASFP    MEASFS    MEASPM
           TRIPLE    VCROSS    VNORM

VDWERR     LIGHTS

VECANG     ANORM     DOT       TRIPLE

VERLET     GRADIENT  MDSAVE    MDSTAT    PRESSURE  RATTLE
           RATTLE2   TEMPER

VERSION    LOWCASE   NEXTARG   TRIMTEXT

VIBRATE    DIAGQ     FATAL     FINAL     FREEUNIT  GETXYZ
           HESSIAN   INITIAL   MECHANIC  NEXTARG   NUMERAL
           PRTXYZ    VERSION

VIBROT     DIAGQ     FINAL     GETINT    HESSROT   INITIAL
           INITROT   MECHANIC

VNORM      ANORM

VOLUME     CONNOLLY

VOLUME1    FATAL

VOLUME2    FATAL

WATSON     ZATOM

WATSON1    GRADRGD   RIGIDXYZ

WRITEOUT   FREEUNIT  NUMERAL   PRTINT    PRTXYZ    VERSION

XTALERR    ENERGY    XTALMOVE  XTALPRM

XTALFIT    FINAL     GETXYZ    INITIAL   MECHANIC  NEXTARG
           SQUARE    XTALPRM

XTALLAT1   ENERGY    LATTICE

XTALMIN    FINAL     FREEUNIT  GETXYZ    GRADIENT  INITIAL
           LATTICE   MECHANIC  NEXTARG   OCVM      PRTXYZ
           TNCG      VERSION   XTALLAT1

XTALMOL1   GRADIENT

XTALMOL2   HESSIAN

XTALMOVE   LATTICE

XTALPRM    BOUNDS    LATTICE   MOLECULE

XYZEDIT    ACTIVE    CUTOFFS   DELETE    FIELD     FINAL
           FREEUNIT  GETXYZ    IMAGE     INERTIA   INITIAL
           INSERT    KATOM     LATTICE   MAKEREF   MERGE
           PRTXYZ    RANDOM    SOAK      SORT      SORT4
           UNITCELL  VERSION

XYZINT     FINAL     FREEUNIT  GETTEXT   GETXYZ    INITIAL
           MAKEINT   NEXTARG   PRTINT    READINT   UPCASE
           VERSION

XYZPDB     FIELD     FINAL     FREEUNIT  GETXYZ    INITIAL
           KATOM     MAKEPDB   MOLECULE  PRTPDB    VERSION

XYZRIGID   JACOBI    ROTEULER

XYZSYBYL   BONDS     FINAL     FREEUNIT  GETXYZ    INITIAL
           PRTMOL2   VERSION

ZATOM      FATAL

ZVALUE     MAKEXYZ   TRIMTEXT
 12.    Examples using the TINKER Package

     This section contains brief  descriptions of the sample 
calculations found in the EXAMPLE subdirectory of the TINKER 
distribution. These examples exercise several of the current 
TINKER programs and are intended  to provide a flavor of the 
capabilities of the package.

ANION Example

Computes an  estimation of the  free energy of  hydration of 
Cl- anion vs.  Br- anion via a 2 picosecond  simulation on a 
``hybrid'' anion in a box of water followed by a free energy 
perturbation calculation

ARGON Example

Performs an  initial energy  minimization on a  periodic box 
containing 150  argon atoms followed  by 6 picoseconds  of a 
molecular  dynamics  using  a  modified  Beeman  integration 
algorithm and a Bersedsen thermostat

CLUSTER Example

Performs a set of 10 Gaussian density annealing (GDA) trials 
on a cluster  of 13 argon atoms in an  attempt to locate the 
global minimum energy structure

CRAMBIN Example

Generates  a TINKER  file from  a  PDB file,  followed by  a 
single  point energy  computation and  determination of  the 
molecular volume and surface area

CYCLOHEX Example

First  approximately locates  the  transition state  between 
chair   and  boat   cyclohexane,   followed  by   subsequent 
refinement of  the transition state and  a final vibrational 
analysis  to  show  that  a  single  negative  frequency  is 
associated with the saddle point

ENKEPHALIN Example

Produces  coordinates  from  the met-enkephalin  amino  acid 
sequence and  phi/psi angles,  followed by  truncated Newton 
energy   minimization  and   determination  of   the  lowest 
frequency normal mode

FORMAMIDE Example

Converts  to  a  unit   cell  from  fractional  coordinates, 
followed   by   full   crystal   energy   minimization   and 
determination of  optimal carbonyl oxygen  energy parameters 
from a fit to lattice energy and structure

HELIX Example

Performs  a rigid-body  optimization of  the packing  of two 
idealized  polyalanine  helices  using only  van  der  Waals 
interactions

SALT Example

Converts   a  sodium   chloride  assymetric   unit  to   the 
corresponding unit  cell, then  runs a  crystal minimization 
starting from the initial  diffraction structure using Ewald 
summation    to   model    the   long-range    electrostatic 
interactions.
 13.    Benchmark Results

     The tables  in this section provide  CPU benchmarks for 
basic TINKER energy  and derivative evaluations, vibrational 
analysis and  molecular dynamics.  All times are  in seconds 
and  were measured  with TINKER  executables dimensioned  to 
maxatm of  10000 and maxhess  of 1000000 in the  source file 
sizes.i. All calculations were run twice in rapid succession 
on a  quiet machine. The  times reported for  each benchmark 
are  the results  from the  second  run. If  you have  built 
TINKER on  an alternative machine  type and are able  to run 
the benchmarks  on the additional machine  type, please send 
the results for inclusion in a future listing.

         BENCHMARK #1:  Calmodulin Energy Evaluation

The  system  is  an  isolated molecule  of  the  148-residue 
protein calmodulin with 2264  atoms using the Amber-94 force 
field. All interactions are computed with no use of cutoffs. 
Times listed are for calculation  setup followed by a single 
energy, energy/gradient and Hessian evaluation.

MACHINE TYPE                  MHz  SETUP  ENERGY  GRAD  HESS

Compaq DS10 (Tru64 5.0)       466  0.35   1.28   1.90   8.05
DEC Alpha 4100 (Tru64 5.0)    400  0.55   2.22   3.92  15.56
SGI IndigoII R10K (Irix 6.5)  195  1.16   3.50   5.93  22.51
Target-USA Athlon (RH 6.2, PGI)950 0.35   0.67   1.59   8.04
Target-USA Athlon (RH 6.2, Absoft)  950   0.33   0.94   1.68
8.58
Target-USA Athlon (RH 6.2, g77)950 0.38   0.91   1.95   9.85
Compaq Armada M700 (RH 6.2, PGI)6500.46   1.35   2.69  14.20
Compaq Armada M700 (RH 6.2, Absoft) 650   0.39   1.46   2.70
15.45
Compaq Armada M700 (RH 6.2, g77)6500.43   1.66   3.65  17.21
Compaq Armada M700 (Win2K, CVF 6.5) 650   0.35   1.29   2.32
12.10
Compaq Armada M700 (Win2K, LF95 5.5)650   0.32   1.83   2.88
15.90


      BENCHMARK #2:  Crambin Crystal Energy Evaluation

The system is a unit  cell of the 46-residue protein crambin 
containing  2 polypeptide  chains, 2  ethanol and  178 water 
molecules for a total of  1360 atoms using the OPLS-UA force 
field. Periodic boundaries are used with particle mesh Ewald 
for electrostatics and a 9.0  Å cutoff for vdW interactions. 
Times listed are for calculation  setup followed by a single 
energy, energy/ gradient and Hessian evaluation.

MACHINE TYPE                  MHz  SETUP  ENERGY  GRAD  HESS

Compaq DS10 (Tru64 5.0)       466  0.28   0.48   0.63   1.78
DEC Alpha 4100 (Tru64 5.0)    400  0.46   0.85   1.08   3.46
SGI IndigoII R10K (Irix 6.5)  195  0.92   1.00   1.43   4.02
Target-USA Athlon (RH 6.2, PGI)950 0.32   0.33   0.48   1.30
Target-USA Athlon (RH 6.2, Absoft)  950   0.26   0.39   0.53
1.67
Target-USA Athlon (RH 6.2, g77)950 0.34   0.46   0.64   1.77
Compaq Armada M700 (RH 6.2, PGI)6500.42   0.52   0.76   2.62
Compaq Armada M700 (RH 6.2, Absoft) 650   0.30   0.62   0.89
3.29
Compaq Armada M700 (RH 6.2, g77)6500.37   0.75   1.02   3.55
Compaq Armada M700 (Win2K, CVF 6.5) 650   0.29   0.51   0.72
2.43
Compaq Armada M700 (Win2K, LF95 5.5)650   0.28   0.61   0.78
3.33


       BENCHMARK #3:  Peptide Normal Mode Calculation

The system is a minimum  energy conformation of a 20-residue 
peptide containing one  of each of the  standard amino acids 
for  a total  of 328  atoms  using the  OPLS-AA force  field 
without cutoffs. The time reported is for computation of the 
Hessian and calculation  of the normal modes  of the Hessian 
matrix and the vibration  frequencies requiring two separate 
matrix diagonalization steps.

MACHINE TYPE                  MHz             NORMAL MODES

Compaq DS10 (Tru64 5.0)       466                  41
DEC Alpha 4100 (Tru64 5.0)    400                  76
SGI IndigoII R10K (Irix 6.5)  195                 145
Target-USA Athlon (RH 6.2, PGI)950                 51
Target-USA Athlon (RH 6.2, Absoft)  950                   54
Target-USA Athlon (RH 6.2, g77)950                 64
Compaq Armada M700 (RH 6.2, PGI)650                66
Compaq Armada M700 (RH 6.2, Absoft) 650                   71
Compaq Armada M700 (RH 6.2, g77)650               119
Compaq Armada M700 (Win2K, CVF 6.5) 650                   63
Compaq Armada M700 (Win2K, LF95 5.5)650                   86


      BENCHMARK #4:  TIP3P Water Box Molecular Dynamics

The system consists of 216  rigid TIP3P water molecules in a 
18.643 Å periodic  box, 9.0 Å shifted  energy switch cutoffs 
for nonbonded  interactions. The  time reported is  for 1000 
dynamics  steps of  1.0 fs  each using  the modified  Beeman 
integrator and Rattle constraints on all bond lengths.

MACHINE TYPE                  MHz               DYNAMICS

Compaq DS10 (Tru64 5.0)       466                 104
DEC Alpha 4100 (Tru64 5.0)    400                 195
SGI IndigoII R10K (Irix 6.5)  195                 278
Target-USA Athlon (RH 6.2, PGI)950                 70
Target-USA Athlon (RH 6.2, Absoft)  950                   77
Target-USA Athlon (RH 6.2, g77)950                125
Compaq Armada M700 (RH 6.2, PGI)650               131
Compaq Armada M700 (RH 6.2, Absoft) 650                  138
Compaq Armada M700 (RH 6.2, g77)650               226
Compaq Armada M700 (Win2K, CVF 6.5) 650                  130
Compaq Armada M700 (Win2K, LF95 5.5)650                  141


     BENCHMARK #5:  TINKER Water Box Molecular Dynamics

The  system  consists  of 216  TINKER  flexible  polarizable 
atomic multipole water molecules in  a 18.643 Å periodic box 
using regular  Ewald summation for the  electrostatics and a 
12.0  Å  switched  cutoff  for vdW  interactions.  The  time 
reported is for 100 dynamics steps  of 1.0 fs each using the 
modified Beeman  integrator and  0.01 Debye  rms convergence 
for induced dipole moments.

MACHINE TYPE                  MHz               DYNAMICS

Compaq DS10 (Tru64 5.0)       466                 304
DEC Alpha 4100 (Tru64 5.0)    400                 527
SGI IndigoII R10K (Irix 6.5)  195                 738
Target-USA Athlon (RH 6.2, PGI)950                243
Target-USA Athlon (RH 6.2, Absoft)  950                  281
Target-USA Athlon (RH 6.2, g77)950                376
Compaq Armada M700 (RH 6.2, PGI)650               443
Compaq Armada M700 (RH 6.2, Absoft) 650                  525
Compaq Armada M700 (RH 6.2, g77)650               811
Compaq Armada M700 (Win2K, CVF 6.5) 650                  411
Compaq Armada M700 (Win2K, LF95 5.5)650                  535
 14.    Collaborators & Acknowledgments

     The TINKER package has developed  over a period of many 
years, very slowly during  the late-1980's, and more rapidly 
since the mid-1990's  in Jay Ponder's research  group at the 
Washington University School of  Medicine in St. Louis. Many 
people have  played significant roles in  the development of 
the package  into its  current form. The  major contributors 
are listed below:


Stew Rubenstein     coordinate interconversions; original 
optimization methods
                    and torsional angle manipulation

Craig Kundrot       molecular surface area & volume and 
their derivatives

Shawn Huston        original AMBER/OPLS implementation; free 
energy
                    calculations; time correlation functions

Mike Dudek          DMA-derived multipole models for 
peptides and proteins

Yong "Mike" Kong    multipole electrostatics; dipole 
polarization; reaction field
                    treatment; TINKER water model

Reece Hart          potential smoothing methodology; 
Scheraga's DEM,
                    Straub's GDA and extensions

Mike Hodsdon        extension of the TINKER distgeom program 
and its
                    application to NMR NOE structure 
determination

Rohit Pappu         potential smoothing methodology and PSS 
algorithms;
                    rigid body optimization; GB/SA solvation 
derivatives

Wijnand Mooij       MM3 directional hydrogen bonding term; 
crystal lattice
                    minimization code

Gerald Loeffler     stochastic/Langevin dynamics 
implementation

Marina Vorobieva    nucleic acid building module and 
parameter translation
Nina Sokolova

Peter Bagossi       TINKER force field parameters for 
alkanes and diatomics

Pengyu Ren          Ewald summation for polarizable atomic 
multipoles;
                    TINKER force field for water, organics 
and peptides

Anders Carlsson     ligand field potential energy term for 
transition metals

Andrey Kutepov      integrator for rigid-body dynamics 
trajectories


In addition,  we would like  to thank Tom Darden  for making 
his  particle mesh  Ewald  code generally  available to  the 
simulation community.

It is  critically important that TINKER's  distributed force 
field  parameter sets  exactly reproduce  the intent  of the 
original force field authors. We  would like to thank Julian 
Tirado-Rives  (OPLS-AA),  Alex   MacKerell  (CHARMM27),  and 
Adrian Roitberg and Carlos Simmerling (AMBER) for their help 
in  testing  TINKER's results  against  those  given by  the 
authentic  programs and  parameter  sets.  Lou Allinger  has 
provided  updated  parameters for  MM2  and  MM3 on  several 
occasions. His very successful methods provided the original 
inspiration for the development of TINKER.

Finally,  we wish  to thank  the  many users  of the  TINKER 
package  for  their  suggestions and  comments,  praise  and 
criticism, which have resulted in a variety of improvements.
 15.    References & Suggested Reading

     This  section  contains a  list  of  the references  to 
general theory, algorithms  and implementation details which 
have  been  of use  during  the  development of  the  TINKER 
package. Methods  described in  some of the  references have 
been implemented  in detail  within the TINKER  source code. 
Other  references  contain   useful  background  information 
although the  algorithms themselves are now  obsolete. Still 
other papers contain ideas  or extensions planned for future 
inclusion  in TINKER.  References for  specific force  field 
parameter sets  are provided in  an earlier section  of this 
User's   Guide.  This   list   is   heavily  skewed   toward 
biomolecules  in general  and proteins  in particular.  This 
bias  reflects  our  group's  major  interests;  however  an 
attempt has  been made  to include  methods which  should be 
generally applicable.

PARTIAL LIST OF MOLECULAR MECHANICS SOFTWARE PACKAGES

AMBER             Peter Kollman,  University of  California, 
San Francisco
AMMP              Rob Harrison, Thomas Jefferson University, 
Philadelphia
ARGOS             Andy McCammon,  University of  California, 
San Diego
BOSS              William Jorgensen, Yale University
BRUGEL            Shoshona   Wodak,   Free   University   of 
Brussels
CFF               Shneior Lifson, Weizmann Institute
CHARMM            Martin Karplus, Harvard University
CHARMM/GEMM       Bernard  Brooks,  National  Institutes  of 
Health, Bethesda
DELPHI            Bastian van de Graaf,  Delft University of 
Technology
DISCOVER          Molecular Simulations Inc., San Diego
DL_POLY           W. Smith  & T.  Forester, CCP5,  Daresbury 
Laboratory
ECEPP             Harold Scheraga, Cornell University
ENCAD             Michael Levitt, Stanford University
FANTOM            Werner   Braun,   University   of   Texas, 
Galveston
FEDER/2           Nobuhiro Go, Kyoto University
GROMACS           Herman Berendsen, University of Groningen
GROMOS            Wilfred van  Gunsteren,  BIOMOS  and  ETH, 
Zurich
IMPACT            Ronald Levy, Rutgers University
MACROMODEL        Schodinger, Inc., Jersey City, New Jersey
MM2/MM3/MM4       N. Lou Allinger, University of Georgia
MMC               Cliff Dykstra, Indiana  Univ.­Purdue Univ. 
at Indianapolis
MMFF              Tom Halgren, Merck  Research Laboratories, 
Rahway
MMTK              Konrad   Hinsen,   Inst.   of   Structural 
Biology, Grenoble
MOIL              Ron Elber, Cornell University
MOLARIS           Arieh  Warshal,  University   of  Southern 
California
MOLDY             Keith Refson, Oxford University
MOSCITO           Dietmar   Paschek    &   Alfons    Geiger, 
Universität Dortmund
NAMD              Klaus Schulten,  University  of  Illinois, 
Urbana
OOMPAA            Andy McCammon,  University of  California, 
San Diego
ORAL              Karel  Zimmerman,   INRA,   Jouy-en-Josas, 
France
ORIENT            Anthony Stone, Cambridge University
PCMODEL           Kevin    Gilbert,     Serena     Software, 
Bloomington, Indiana
PEFF              Jan Dillen, University of  Pretoria, South 
Africa
Q                 Johan Åqvist, Uppsala University
SIBFA             Nohad Gresh, INSERM, CNRS, Paris
SIGMA             Jan Hermans, University of North Carolina
SPASIBA           Gerard Vergoten, Université de Lille
SPASMS            David Spellmeyer  and  the Kollman  Group, 
UCSF
TINKER            Jay  Ponder,  Washington  University,  St. 
Louis
XPLOR/CNS         Axel Brünger, Stanford University
YAMMP             Stephen  Harvey,  University  of  Alabama, 
Birmingham
YASP              Florian   Mueller-Plathe,   ETH   Zentrum, 
Zurich
YETI              Angelo Vedani, Biografik-Labor 3R, Basel

AMBER     D. A  Pearlman, D. A. Case, J. W.  Caldwell, W. S. 
Ross, T. E. Cheatham III,  S. DeBolt, D. Ferguson, G. Seibel 
and P.  Kollman, AMBER, a  Package of Computer  Programs for 
Applying   Molecular   Mechanics,  Normal   Mode   Analysis, 
Molecular Dynamics and Free  Energy Calculations to Simulate 
the Structural and Energetic  Properties of Molecules, Comp. 
Phys. Commun., 91, 1-41 (1995)

ARGOS      T. P.  Straatsma  and J.  A.  McCammon, ARGOS,  a 
Vectorized  General Molecular  Dynamics Program,  J. Comput. 
Chem., 11, 943-951 (1990)

CHARMM     B. R. Brooks, R. E. Bruccoleri, B. D. Olafson, D. 
J. States, S. Swaminathan and  M. Karplus, CHARMM: A Program 
for  Macromolecular   Energy,  Minimization,   and  Dynamics 
Calculations, J. Comput. Chem., 4, 187-217 (1983)

ENCAD     M. Levitt, M. Hirshberg, R. Sharon and V. Daggett, 
Potential Energy Function and Parameters for Simulations for 
the  Molecular Dynamics  of  Proteins and  Nucleic Acids  in 
Solution, Comp. Phys. Commun., 91, 215-231 (1995)

FANTOM      T.  Schaumann, W.  Braun  and  K. Wurtrich,  The 
Program  FANTOM for  Energy Refinement  of Polypeptides  and 
Proteins Using  a Newton-Raphson Minimizer in  Torsion Angle 
Space, Biopolymers, 29, 679-694 (1990)

FEDER/2      H.  Wako,  S.  Endo, K.  Nagayama  and  N.  Go, 
FEDER/2:  Program  for  Static  and  Dynamic  Conformational 
Energy Analysis of Macro-molecules  in Dihedral Angle Space, 
Comp. Phys. Commun., 91, 233-251 (1995)

GROMACS     H. J. C. Berendsen, D.  van der Spoel and R. van 
Drunen,  GROMACS:   A  Message-passing   Parallel  Molecular 
Dynamics  Implementation,  Comp.  Phys. Commun.,  91,  43-56 
(1995)

GROMOS     W. R. P. Scott, P. H. Hunenberger , I. G. Tironi, 
A.  E. Mark,  S. R.  Billeter, J.  Fennen, A.  E. Torda,  T. 
Huber,  P.   Kruger,  W.   F.  van  Gunsteren,   The  GROMOS 
Biomolecular Simulation  Program Package, J. Phys.  Chem. A, 
103, 3596-3607 (1999)

IMPACT     D.  B. Kitchen,  F. Hirata,  J. D.  Westbrook, R. 
Levy,  D. Kofke  and  M. Yarmush,  Conserving Energy  during 
Molecular  Dynamics  Simulations  of  Water,  Proteins,  and 
Proteins in Water, J. Comput. Chem., 10, 1169-1180 (1990)

MACROMODEL     F. Mahamadi, N. G.  J. Richards, W. C. Guida, 
R. Liskamp, M. Lipton, C. Caufield, G. Chang, T. Hendrickson 
and W.  C. Still,  MacroModel­An Integrated  Software System 
for   Modeling  Organic   and  Bioorganic   Molecules  Using 
Molecular Mechanics, J. Comput. Chem., 11, 440-467 (1990)

MM2     N. L. Allinger, Conformational Analysis. 130. MM2. A 
Hydrocarbon Force Field Utilizing V1 and V2 Torsional Terms, 
J. Am. Chem. Soc., 99, 8127-8134 (1977)

MM3     N. L.  Allinger, Y. H. Yuh and  J.-H. Lii, Molecular 
Mechanics.  The MM3  Force  Field for  Hydrocarbons, J.  Am. 
Chem. Soc., 111, 8551-8566 (1989)

MM4     N. L.  Allinger, K. Chen and J.-H.  Lii, An Improved 
Force  Field (MM4)  for Saturated  Hydrocarbons, J.  Comput. 
Chem., 17, 642-668 (1996)

MMC      C.  E.  Dykstra,  Molecular  Mechanics  for  Weakly 
Interacting  Assemblies   of  Rare   Gas  Atoms   and  Small 
Molecules, J. Am. Chem. Soc., 111, 6168-6174 (1989)

MMFF      T. A.  Halgren,  Merck Molecular  Force Field.  I. 
Basis,  Form, Scope,  Parameterization,  and Performance  of 
MMFF94, J. Comput. Chem., 17, 490-516 (1996)

MOIL     R. Elber, A. Roitberg, C. Simmerling, R. Goldstein, 
H. Li,  G. Verkhiver,  C. Keasar, J.  Zhang and  A. Ulitsky, 
MOIL:  A Program  for Simulations  of Macromolecules,  Comp. 
Phys. Commun., 91, 159-189 (1995)

MOSCITO      See the  web  site at  http:/ganter.chemie.uni-
dortmund.de/~pas/moscito.html

NAMD     L.  Kalé, R. Skeel,  M. Bhandarkar, R.  Brunner, A. 
Gursoy,   N.  Krawetz,   J.  Phillips,   A.  Shinozaki,   K. 
Varadarajan and K. Schulten,  NAMD2: Greater Scalability for 
Parallel Molecular Dynamics, J.  Comput. Phys., 151, 283-312 
(1999)

OOMPAA     G.  A. Huber  and J. A.  McCammon, OOMPAA­Object-
oriented Model for Probing  Assemblages of Atoms, J. Comput. 
Phys., 151, 264-282 (1999)

ORAL       K.  Zimmermann,   ORAL:  All   Purpose  Molecular 
Mechanics Simulator and Energy  Minimizer, J. Comput. Chem., 
12, 310-319 (1991)

PCMODEL     See the web site at http:/www.serenasoft.com

PEFF      J.  L.   M.  Dillen,  PEFF:  A   Program  for  the 
Development of Empirical Force Fields, J. Comput. Chem., 13, 
257-267 (1992)

Q     See the web site at http://aqvist.bmc.uu.se/Q

SIBFA     N. Gresh,  Inter- and Intramolecular Interactions. 
Inception and Refinements of  the SIBFA, Molecular Mechanics 
(SMM)  Procedure,   a  Separable,   Polarizable  Methodology 
Grounded  on ab  Initio  SCF/MP2  Computations. Examples  of 
Applications  to Molecular  Recognition  Problems, J.  Chim. 
Phys. PCB, 94, 1365-1416 (1997)

SIGMA     See the web site at http://femto.med.unc.edu/SIGMA

SPASIBA       P.  Derreumaux   and   G.   Vergoten,  A   New 
Spectroscopic Molecular  Mechanics Force-Field  - Parameters 
For Proteins, J. Chem. Phys., 102, 8586-8605 (1995)

TINKER           See       the       web       site       at 
http://dasher.wustl.edu/tinker

YAMMP     R. K.-Z. Tan and  S. C. Harvey, Yammp: Development 
of  a   Molecular  Mechanics   Program  Using   the  Modular 
Programming Method, J. Comput. Chem., 14, 455-470 (1993)

YETI       A.  Vedani,   YETI:   An   Interactive  Molecular 
Mechanics Program  for Small-Molecule Protein  Complexes, J. 
Comput. Chem., 9, 269-280 (1988)

MOLECULAR MECHANICS

U. Burkert and N. L. Allinger, Molecular Mechanics, American 
Chemical Society, Washington, D.C., 1982

K. Rasmussen,  Potential Energy Functions  in Conformational 
Analysis (Lecture  Notes in  Chemistry, Vol.  27), Springer-
Verlag, Berlin, 1985

A. K.  Rappé and C.  J. Casewit, Molecular  Mechanics across 
Chemistry, University Science Books, Sausalito, CA, 1997

K. Machida, Principles of Molecular Mechanics, Kodansha/John 
Wiley & Sons, Tokyo/New York, 1999

P. Comba and T. W.  Hambley, Molecular Modeling of Inorganic 
Compounds, VCH, New York, 1995

COMPUTER SIMULATION METHODS

M. J. Field,  A Practical Introduction to  the Simulation of 
Molecular Systems, Cambridge Univ. Press, Cambridge, 1999

A.   R.   Leach,   Molecular   Modelling:   Principles   and 
Applications, Addison Wesley Longman, Essex, England, 1996

D. Frankel and B.  Smit, Understanding Molecular Simulation: 
From Algorithms to Applications,  Academic Press, San Diego, 
CA, 1996

D. C.  Rapaport, The  Art of Molecular  Dynamics Simulation, 
Cambridge University Press, Cambridge, 1995

J. M.  Haile, Molecular Dynamics Simulation,  John Wiley and 
Sons, New York, 1992

M.  P. Allen  and D.  J. Tildesley,  Computer Simulation  of 
Liquids, Oxford University Press, Oxford, 1987

T. Schlick,  R. D. Skeel, A.  T. Brünger, L. V.  Kale, J. A. 
Board, J. Hermans and K. Schulten, Algorithmic Challenges in 
Computational Molecular  Biophysics, J. Comput.  Phys., 151, 
9-48 (1999)

MODELING OF BIOLOGICAL MACROMOLECULES

J.  A. McCammon  and  S. Harvey,  Dynamics  of Proteins  and 
Nucleic Acids, Cambridge University Press, Cambridge, 1987

C. L. Brooks III, M. Karplus  and B. M. Pettitt, Proteins: A 
Theoretical   Perspective   of  Dynamics,   Structure,   and 
Thermodynamics, John Wiley and Sons, New York, 1988

W.  F. van  Gunsteren, P.  K.  Weiner and  A. J.  Wilkinson, 
Computer  Simulation  of  Biomolecular  Systems,  Vol.  1-3, 
Kluwer Academic Publishers, Dordrecht, 1989-1997

T.  E.  Cheatham  and  B.  R.  Brooks,  Recent  Advances  in 
Molecular   Dynamics   Simulation  towards   the   Realistic 
Representation  of Biomolecules  in  Solution, Theor.  Chem. 
Acc., 99, 279-288 (1998)

CONJUGATE GRADIENT  AND QUASI-NEWTON OPTIMIZATION

J.  Nocedal  and  S.   J.  Wright,  Numerical  Optimization, 
Springer-Verlag, New York, 1999

S. G. Nash  and A. Sofer, Linear  and Nonlinear Programming, 
McGraw-Hill, New York, 1996

R. Fletcher, Practical Methods of Optimization, John Wiley & 
Sons Ltd., Chichester, 1987

D. G. Luenberger, Linear and Nonlinear Programming, 2nd Ed., 
Addison-Wesley, Reading, MA, 1984

P.  E.  Gill,   W.  Murray  and  M.   H.  Wright,  Practical 
Optimization, Academic Press, New York, 1981

J.  Nocedal,  Updating  Quasi-Newton Matrices  with  Limited 
Storage, Math. Comp., 773-782 (1980)

S. J. Watowich,  E. S. Meyer, R. Hagstrom and  R. Josephs, A 
Stable,  Rapidly Converging  Conjugate  Gradient Method  for 
Energy Minimization, J. Comput. Chem., 9, 650-661 (1988)

W. C. Davidon, Optimally Conditioned Optimization Algorithms 
without Line Searches, Math. Prog., 9, 1-30 (1975)

TRUNCATED NEWTON OPTIMIZATION

J. W.  Ponder and F.  M. Richards, An  Efficient Newton-like 
Method for Molecular Mechanics  Energy Minimization of Large 
Molecules, J. Comput. Chem., 8, 1016-1024 (1987)

R. S. Dembo and T. Steihaug, Truncated-Newton Algorithms for 
Large-Scale  Unconstrained  Optimization, Math.  Prog.,  26, 
190-212 (1983)

S. C. Eisenstat and H. F. Walker, Choosing the Forcing Terms 
in an Inexact Newton Method, SIAM J. Sci. Comput., 17, 16-32 
(1996)

T.  Schlick  and M.  Overton,  A  Powerful Truncated  Newton 
Method for Potential Energy  Minimization, J. Comput. Chem., 
8, 1025-1039 (1987)

D.  S. Kershaw,  The Incomplete  Cholesky-Conjugate Gradient 
Method  for  the Iterative  Solution  of  Systems of  Linear 
Equations, J. Comput. Phys., 26, 43-65 (1978)

T. A. Manteuffel, An  Incomplete Factorization Technique for 
Positive Definite  Linear Systems, Math. Comp.,  34, 473-497 
(1980)

P. Derreumaux, G.  Zhang and T. Schlick and B.  R. Brooks, A 
Truncated   Newton   Minimizer   Adapted  for   CHARMM   and 
Biomolecular  Applications, J.  Comput.  Chem., 15,  532-552 
(1994)

I. S. Duff, A. M. Erisman and J. K. Reid, Direct Methods for 
Sparse Matrices, Oxford University Press, Oxford, 1986

POTENTIAL ENERGY SMOOTHING

R.  V. Pappu,  R. K.  Hart and  J. W.  Ponder, Analysis  and 
Application of Potential Energy Smoothing Methods for Global 
Optimization, J. Phys. Chem. B, 102, 9725-9742 (1998)

L. Piela, J.  Kostrowicki and H. A.  Scheraga, The Multiple-
Minima Problem in the  Conformational Analysis of Molecules. 
Deformation  of the  Potential  Energy  Hypersurface by  the 
Diffusion  Equation Method,  J. Phys.  Chem., 93,  3339-3346 
(1989)

J.  Ma  and J.  E.  Straub,  Simulated Annealing  Using  the 
Classical Density Distribution, J. Chem. Phys., 101, 533-541 
(1994)

C. Tsoo  and C.  L. Brooks, Cluster  Structure Determination 
Using  Gaussian  Density  Distribution  Global  Minimization 
Methods, J. Chem. Phys., 101, 6405-6411 (1994)

S.   Nakamura,  H.   Hirose,   M.  Ikeguchi   and  J.   Doi, 
Conformational Energy Minimization Using a Two-Stage Method, 
J. Phys. Chem., 99, 8374-8378 (1995)

T. Huber,  A. E.  Torda and W.  F. van  Gunsteren, Structure 
Optimization Combining Soft-Core  Interaction Functions, the 
Diffusion Equation Method, and  Molecular Dynamics, J. Phys. 
Chem. A, 101, 5926-5930 (1997)

S.  Schelstraete and  H. Verschelde,  Finding Minimum-Energy 
Configurations of Lennard-Jones  Clusters Using an Effective 
Potential, J. Phys. Chem. A, 101, 310-315 (1998)

I. Andricioaei  and J. E. Straub,  Global Optimization Using 
Bad Derivatives: Derivative-Free Method for Molecular Energy 
Minimization, J. Comput. Chem., 19, 1445-1455 (1998)

L. Piela, Search for the Most Stable Structures on Potential 
Energy Surfaces,  Coll. Czech. Chem. Commun.,  63, 1368-1380 
(1998)

``SNIFFER'' GLOBAL OPTIMIZATION

A. O. Griewank, Generalized Descent for Global Optimization, 
J. Opt. Theor. Appl., 34, 11-39 (1981)

R. A.  R. Butler and  E. E.  Slaminka, An Evaluation  of the 
Sniffer  Global Optimization  Algorithm Using  Standard Test 
Functions, J. Comput. Phys., 99, 28-32 (1993)

J. W.  Rogers and  R. A. Donnelly,  Potential Transformation 
Methods for Large-Scale Global Optimization, SIAM J. Optim., 
5, 871-891 (1995)

INTEGRATION METHODS FOR MOLECULAR DYNAMICS

D.  Beeman,  Some Multistep  Methods  for  Use in  Molecular 
Dynamics Calculations, J. Comput. Phys., 20, 130-139 (1976)

M. Levitt  and H.  Meirovitch, Integrating the  Equations of 
Motion, J. Mol. Biol., 168, 617-620 (1983)

J. Aqvist, W. F. van Gunsteren, M. Leijonmarck and O. Tapia, 
A Molecular Dynamics Study of the C-Terminal Fragment of the 
L7/L12 Ribosomal Protein, J. Mol. Biol., 183, 461-477 (1985)

W. C. Swope, H. C. Andersen,  P. H. Berens and K. R. Wilson, 
A  Computer   Simulation  Method  for  the   Calculation  of 
Equilibrium Constants for the Formation of Physical Clusters 
of Molecules: Application to  Small Water Clusters, J. Chem. 
Phys., 76, 637-649 (1982)

CONSTRAINT DYNAMICS

W. F. van  Gunsteren and H. J. C.  Berendsen, Algorithms for 
Macromolecular Dynamics and Constraint Dynamics, Mol. Phys., 
34, 1311-1327 (1977)

G.  Ciccotti,  M.  Ferrario and  J.-P.  Ryckaert,  Molecular 
Dynamics  of  Rigid  Systems  in  Cartesian  Coordinates:  A 
General Formulation, Mol. Phys., 47, 1253-1264 (1982)

H. C. Andersen, Rattle: A  ``Velocity'' Version of the Shake 
Algorithm  for Molecular  Dynamics Calculations,  J. Comput. 
Phys., 52, 24-34 (1983)

R. Kutteh, RATTLE Recipe  for General Holonomic Constraints: 
Angle  and Torsion  Constraints, CCP5  Newsletter, 46,  9-17 
(1998)     [available    from     the     web    site     at 
http://www.dl.ac.uk/CCP/CCP5/newsletter_index.html]

B. J.  Palmer, Direct Application  of SHAKE to  the Velocity 
Verlet Algorithm, J. Comput. Phys., 104, 470-472 (1993)

S. Miyamoto and P. A. Kollman, SETTLE: An Analytical Version 
of the SHAKE and RATTLE Algorithm for Rigid Water Models, J. 
Comput. Chem., 13, 952-962 (1992)

B.  Hess, H.  Bekker, H.  J. C.  Berendsen and  J. G.  E. M. 
Fraaije,  LINCS: A  Linear Constraint  Solver for  Molecular 
Simulations, J. Comput. Chem., 18, 1463-1472 (1997)

J. T.  Slusher and P. T.  Cummings, Non-Iterative Constraint 
Dynamics  using   Velocity-Explicit  Verlet   Methods,  Mol. 
Simul., 18, 213-224 (1996)

LANGEVIN, BROWNIAN AND STOCHASTIC DYNAMICS

M.  P. Allen,  Brownian  Dynamics Simulation  of a  Chemical 
Reaction in Solution, Mol. Phys., 40, 1073-1087 (1980)

W. F. van  Gunsteren and H. J. C.  Berendsen, Algorithms for 
Brownian Dynamics, Mol. Phys., 45, 637-647 (1982)

F.  Guarnieri   and  W.  C.  Still,   A  Rapidly  Convergent 
Simulation Method: Mixed Monte Carlo/Stochastic Dynamics, J. 
Comput. Chem., 15, 1302-1310 (1994)

M.  G. Paterlini  and D.  M. Ferguson,  Constant Temperature 
Simulations using the Langevin Equation with Velocity Verlet 
Integration, Chem. Phys., 236, 243-252 (1998)

CONSTANT TEMPERATURE AND PRESSURE DYNAMICS

H. J. C. Berendsen, J. P. M. Postma, W. F. van Gunsteren, A. 
DiNola and J.  R. Haak, Molecular Dynamics  with Coupling to 
an External Bath, J. Chem. Phys., 81, 3684-3690 (1984)

W.  G. Hoover,  Canonical Dynamics:  Equilibrium Phase-space 
Distributions, Phys. Rev. A, 31, 1695-1697 (1985)

J.  J.  Morales,  S.  Toxvaerd  and  L.  F.  Rull,  Computer 
Simulation of a Phase Transition at Constant Temperature and 
Pressure, Phys. Rev. A, 34, 1495-1498 (1986)

B. R. Brooks, Algorithms  for Molecular Dynamics at Constant 
Temperature  and Pressure,  Internal Report  of Division  of 
Computer  Research and  Technology,  National Institutes  of 
Health, 1988.

M. Levitt,  Molecular Dynamics  of Native  Protein: Computer 
Simulation  of Trajectories,  J.  Mol.  Biol., 168,  595-620 
(1983)

OUT-OF-PLANE DEFORMATION TERMS

J. R. Maple, U. Dinar and  A. T. Hagler, Derivation of Force 
Fields for  Molecular Mechanics and Dynamics  from ab initio 
Energy Surfaces,  Proc. Natl. Acad. Sci.  USA, 85, 5350-5354 
(1988)

S.-H. Lee, K. Palmo and S. Krimm, New Out-of-Plane Angle and 
Bond Angle Internal Coordinates and Related Potential Energy 
Functions for Molecular  Mechanics and Dynamics Simulations, 
J. Comput. Chem., 20, 1067-1084 (1999)

ANALYTICAL DERIVATIVES OF POTENTIAL FUNCTIONS

K. J. Miller, R. J. Hinde  and J. Anderson, First and Second 
Derivative Matrix Elements for  the Stretching, Bending, and 
Torsional Energy, J. Comput. Chem., 10, 63-76 (1989)

D.  H. Faber  and C.  Altona, UTAH5:  A Versatile  Programme 
Package for the Calculation of Molecular Properties by Force 
Field Methods, Computers & Chemistry, 1, 203-213 (1977)

W. C. Swope and D.  M. Ferguson, Alternative Expressions for 
Energies  and  Forces Due  to  Angle  Bending and  Torsional 
Energy,  Report G320-3561,  J.  Comput.  Chem., 13,  585-594 
(1992)

A. Blondel  and M. Karplus, New  Formulation for Derivatives 
of Torsion  Angles and Improper Torsion  Angles in Molecular 
Mechanics: Elimination  of Singularities, J.  Comput. Chem., 
17, 1132-1141 (1996)

R.  E.  Tuzun, D.  W.  Noid  and  B. G.  Sumpter,  Efficient 
Treatment   of  Out-of-Plane   Bend  and   Improper  Torsion 
Interactions  in  MM2,  MM3,  and  MM4  Molecular  Mechanics 
Calculations, J. Comput. Chem., 18, 1804-1811 (1997)

TORSIONAL SPACE DERIVATIVES AND NORMAL MODES

M. Levitt,  C. Sander and  P. S. Stern,  Protein Normal-mode 
Dynamics:   Trypsin  Inhibitor,  Crambin,  Ribonuclease  and 
Lysozyme, J. Mol. Biol., 181, 423-447 (1985)

M. Levitt, Protein Folding by Restrained Energy Minimization 
and Molecular Dynamics, J. Mol. Biol., 170, 723-764 (1983)

H.  Wako  and N.  Go,  Algorithm  for Rapid  Calculation  of 
Hessian  of Conformational  Energy Function  of Proteins  by 
Supercomputer, J. Comput. Chem., 8, 625-635 (1987)

H. Abe, W. Braun, T. Noguti  and N. Go, Rapid Calculation of 
First and  Second Derivatives of Conformational  Energy with 
Respect to  Dihedral Angles for Proteins:  General Recurrent 
Equations, Computers & Chemistry, 8, 239-247 (1984)

T.  Noguti and N.  Go, A  Method of  Rapid Calculation  of a 
Second Derivative Matrix of  Conformational Energy for Large 
Molecules, J. Phys. Soc. Japan, 52, 3685-3690 (1983)

ANALYTICAL SURFACE AREA AND VOLUME

M. L. Connolly, Analytical Molecular Surface Calculation, J. 
Appl. Cryst., 16, 548-558 (1983)

M.  L. Connolly,  Computation  of Molecular  Volume, J.  Am. 
Chem. Soc., 107, 1118-1124 (1985)

M. L. Connolly, Molecular Surfaces: A Review, available from 
the                web                site                at 
http://www.netsci.org/Science/Compchem/feature14.html

C. E. Kundrot,  J. W. Ponder and F.  M. Richards, Algorithms 
for  Calculating Excluded  Volume and  Its Derivatives  as a 
Function of  Molecular Conformation and Their  Use in Energy 
Minimization, J. Comput. Chem., 12, 402-409 (1991)

T. J. Richmond, Solvent Accessible Surface Area and Excluded 
Volume in Proteins, J. Mol. Biol., 178, 63-89 (1984)

L.  Wesson and  D.  Eisenberg,  Atomic Solvation  Parameters 
Applied  to  Molecular  Dynamics of  Proteins  in  Solution, 
Protein Science, 1, 227-235 (1992)

V. Gononea and E. Osawa, Implementation of Solvent Effect in 
Molecular  Mechanics, Part  3. The  First- and  Second-order 
Analytical Derivatives  of Excluded Volume, J.  Mol. Struct. 
(Theochem), 311 305-324 (1994)

K. D.  Gibson and H.  A. Scheraga, Exact Calculation  of the 
Volume and Surface Area  of Fused Hard-sphere Molecules with 
Unequal Atomic Radii, Mol. Phys., 62, 1247-1265 (1987)

K.  D.  Gibson and  H.  A.  Scheraga,  Surface Area  of  the 
Intersection  of   Three  Spheres  with  Unequal   Radii:  A 
Simplified  Analytical  Formula,  Mol.  Phys.,  64,  641-644 
(1988)

S. Sridharan, A. Nichols and K. A. Sharp, A Rapid Method for 
Calculating Derivatives of  Solvent Accessible Surface Areas 
of Molecules, J. Comput, Chem., 16, 1038-1044 (1995)

APPROXIMATE SURFACE AREA AND VOLUME

S. J.  Wodak and J.  Janin, Analytical Approximation  to the 
Accessible Surface Area of  Proteins, Proc. Natl. Acad. Sci. 
USA, 77, 1736-1740 (1980)

W.  Hasel,  T. F.  Hendrickson  and  W.  C. Still,  A  Rapid 
Approximation  to the  Solvent Accessible  Surface Areas  of 
Atoms, Tetrahedron Comput. Method., 1, 103-116 (1988)

J.  Weiser,  P. S.  Shenkin  and  W. C.  Still,  Approximate 
Solvent-Accessible Surface Areas from Tetrahedrally Directed 
Neighber Densities, Biopolymers, 50, 373-380 (1999)

BOUNDARY CONDITIONS AND NEIGHBOR METHODS

W.  F. van  Gunsteren, H.  J. C.  Berendsen, F.  Colonna, D. 
Perahia,  J. P.  Hollenberg  and D.  Lellouch, On  Searching 
Neighbors in Computer Simulations of Macromolecular Systems, 
J. Comput. Chem., 5, 272-279  (1984)

F.  Sullivan, R.  D.  Mountain and  J. O'Connell,  Molecular 
Dynamics on Vector Computers,  J. Comput. Phys., 61, 138-153 
(1985)

J. Boris, A Vectorized ``Near Neighbors'' Algorithm of Order 
N Using a Monotonic Logical Grid, J. Comput. Phys., 66, 1-20 
(1986)

S. G. Lambrakos and J. P. Boris, Geometric Properties of the 
Monotonic  Lagrangian  Grid  Algorithm  for  Near  Neighbors 
Calculations, J. Comput. Phys., 73, 183-202 (1987)

T. A.  Andrea, W. C. Swope  and H. C. Andersen,  The Role of 
Long  Ranged   Forces  in  Determining  the   Structure  and 
Properties of  Liquid Water,  J. Chem. Phys.,  79, 4576-4584 
(1983)

D. N. Theodorou and  U. W. Suter, Geometrical Considerations 
in Model Systems with Periodic Boundary Conditions, J. Chem. 
Phys., 82, 955-966 (1985)

J.  Barnes  and  P.  Hut,  A  Hierarchical  O(NlogN)  Force-
calculation Algorithm, Nature, 234, 446-449 (1986)

CUTOFF AND TRUNCATION METHODS

P.  J.  Steinbach and  B.  R.  Brooks, New  Spherical-Cutoff 
Methods for Long-Range  Forces in Macromolecular Simulation, 
J. Comput. Chem., 15, 667-683 (1993)

R. J. Loncharich and B. R. Brooks, The Effects of Truncating 
Long-Range Forces  on Protein  Dynamics, Proteins,  6, 32-45 
(1989)

C. L. Brooks  III, B. M. Pettitt and  M. Karplus, Structural 
and Energetic Effects of Truncating Long Ranged Interactions 
in Ionic  and Polar  Fluids, J.  Chem. Phys.,  83, 5897-5908 
(1985)

EWALD SUMMATION TECHNIQUES

A.  Y.  Toukmaji  and  J. A.  Board,  Jr.,  Ewald  Summation 
Techniques in  Perspective: A  Survey, Comp.  Phys. Commun., 
95, 73-92 (1996)

T. Darden, L. Perera, L. Li  and L. Pedersen, New Tricks for 
Modelers from the Crystallography Toolkit: The Particle Mesh 
Ewald  Algorithm and  its Use  in Nucleic  Acid Simulations, 
Structure, 7, R550-R60 (1999)

T. Darden, D. York and  L. G. Pedersen, Particle Mesh Ewald: 
An N·log(N) Method for Ewald Sums in Large Systems, J. Chem. 
Phys., 98, 10089-10092 (1993)

U. Essmann,  L. Perera, M.  L. Berkowitz, T. Darden,  H. Lee 
and L. G. Pedersen, A  Smooth Particle Mesh Ewald Method, J. 
Chem. Phys., 103, 8577-8593 (1995)

W.   Smith,  Point   Multipoles  in   the  Ewald   Summation 
(Revisited), CCP5  Newsletter, 46, 18-30  (1998)  [available 
from http://www.dl.ac.uk/CCP/CCP5/newsletter_index.html]

S. E. Feller, R. W. Pastor, A. Rojnuckarin, S. Bogusz and B. 
R.  Brooks,  Effect  of Electrostatic  Force  Truncation  on 
Interfacial  and Transport  Properties  of  Water, J.  Phys. 
Chem., 100, 17011-17020 (1996)

W. Weber,  P. H. Hünenberger  and J. A.  McCammon, Molecular 
Dynamics  Simulations  of  a Polyalanine  Octapeptide  under 
Ewald   Boundary   Conditions:   Influence   of   Artificial 
Periodicity on Peptide Conformation,  J. Phys. Chem. B, 104, 
3668-3675 (2000)

CONJUGATED AND AROMATIC SYSTEMS

N.  L. Allinger,  F. Li,  L. Yan  and J.  C. Tai,  Molecular 
Mechanics (MM3) Calculations  on Conjugated Hydrocarbons, J. 
Comput. Chem., 11, 868-895 (1990)

J. T.  Sprague, J. C.  Tai, Y. Yuh  and N. L.  Allinger, The 
MMP2  Calculational Method,  J.  Comput.  Chem., 8,  581-603 
(1987)

J.  Kao,  A  Molecular  Orbital  Based  Molecular  Mechanics 
Approach  to Study  Conjugated  Hydrocarbons,  J. Am.  Chem. 
Soc., 109, 3818-3829 (1987)

J. Kao and N. L. Allinger, Conformational Analysis: Heats of 
Formation  of Conjugated  Hydrocarbons  by  the Force  Field 
Method, J. Am. Chem. Soc., 99, 975-986 (1977)

D. H. Lo and M.  A. Whitehead, Accurate Heats of Atomization 
and Accurate  Bond Lengths: Benzenoid Hydrocarbons,  Can. J. 
Chem., 46, 2027-2040 (1968)

G. D.  Zeiss and  M. A. Whitehead,  Hetero-atomic Molecules: 
Semi-empirical Molecular Orbital Calculations and Prediction 
of Physical Properties, J. Chem. Soc. A, 1727-1738 (1971)

FREE ENERGY SIMULATION METHODS

P.  Kollman,  Free   Energy  Calculations:  Applications  to 
Chemical and  Biochemical Phenomena,  Chem. Rev.,  93, 2395-
2417 (1993)

B.   L.   Tembe   and  J.   A.   McCammon,   Ligand-Receptor 
Interactions, Computers & Chemistry, 8, 281-283 (1984)

W. L. Jorgensen and C.  Ravimohan, Monte Carlo Simulation of 
Differences in Free Energy of Hydration, J. Chem. Phys., 83, 
3050-3054 (1985)

W. L.  Jorgensen, J.  K. Buckner, S.  Boudon and  J. Tirado-
Rives, Efficient  Computation of  Absolute Free  Energies of 
Binding by Computer Simulations:  Application to the Methane 
Dimer in Water, J. Chem. Phys., 89, 3742-3746 (1988)

S. H.  Fleischman and  C. L.  Brooks III,  Thermodynamics of 
Aqueous  Solvation:   Solution  Properties of  Alcohols  and 
Alkanes, J. Chem. Phys., 87, 3029-3037 (1987)

U. C. Singh,  F. K. Brown, P. A. Bash and  P. A. Kollman, An 
Approach  to the  Application  of  Free Energy  Perturbation 
Methods Using  Molecular Dynamics,  J. Am. Chem.  Soc., 109, 
1607-1614 (1987)

D. A. Pearlman and P. A.  Kollman, A New Method for Carrying 
out  Free  Energy   Perturbation  Calculations:  Dynamically 
Modified Windows, J. Chem. Phys., 90, 2460-2470 (1989)

T. P.  Straatsma, H. J.  C. Berendsen  and J. P.  M. Postma, 
Free Energy of Hydrophobic  Hydration:  A Molecular Dynamics 
Study of Noble Gases in Water, J. Chem. Phys., 85, 6720-6727 
(1986)

T. P. Straatsma and H. J. C. Berendsen, Free Energy of Ionic 
Hydration:    Analysis   of  a   Thermodynamic   Integration 
Technique to  Evaluate Free Energy Differences  by Molecular 
Dynamics Simulations, J. Chem. Phys., 89, 5876-5886 (1988)

M. Mezei,  The Finite Difference  Thermodynamic Integration, 
Tested on  Calculating the Hydration Free  Energy Difference 
between Acetone and Dimethylamine  in Water, J. Chem. Phys., 
86, 7084-7088 (1987)

A. E.  Mark and  W. F. van  Gunsteren, Decomposition  of the 
Free Energy of  a System in Terms  of Specific Interactions, 
J. Mol. Biol., 240, 167-176 (1994)

S.  Boresch  and  M.  Karplus,  The  Meaning  of  Copmponent 
Analysis:  Decomposition  of the  Free  Energy  in Terms  of 
Specific Interactions, J. Mol. Biol., 254, 801-807 (1995)

METHODS FOR PARAMETER DETERMINATION

N. L. Allinger, X. Zhou  and J. Bergsma, Molecular Mechanics 
Parameters, J. Mol. Struct. (THEOCHEM), 312, 69-83 (1994)

A.  J.  Pertsin  and  A.  I.  Kitaigorodsky,  The  Atom-Atom 
Potential Method:  Application to Organic  Molecular Solids, 
Springer-Verlag, Berlin, 1987

D. E.  Williams, Transferable Empirical  Nonbonded Potential 
Functions, in Crystal  Cohesion and Conformational Energies, 
Ed. by R. M. Metzger, Springer-Verlag, Berlin, 1981

A. T. Hagler and S. Lifson, A Procedure for Obtaining Energy 
Parameters from Crystal Packing, Acta Cryst., B30, 1336-1341 
(1974)

A.  T. Hagler,  S. Lifson  and P.  Dauber, Consistent  Force 
Field  Studies of  Intermolecular Forces  in Hydrogen-Bonded 
Crystals:   A  Benchmark  for the  Objective  Comparison  of 
Alternative Force Fields, J.  Am. Chem. Soc., 101, 5122-5130 
(1979)

W. L. Jorgensen,  J. D. Madura and C.  J. Swenson, Optimized 
Intermolecular Potential Functions  for Liquid Hydrocarbons, 
J. Am. Chem. Soc., 106, 6638-6646 (1984)

W. L. Jorgensen and  C. J. Swenson, Optimized Intermolecular 
Potential Functions  for Amides and Peptides:  Structure and 
Properties of Liquid Amides, J. Am. Chem. Soc., 107, 569-578 
(1985)

J. R. Maple, U. Dinur and  A. T. Hagler, Derivation of Force 
Fields for  Molecular Mechanics and Dynamics  from ab Initio 
Surfaces, Proc. Nat. Acad. Sci. USA, 85, 5350-5354 (1988)

U. Dinur and  A. T. Hagler, Direct  Evaluation of Nonbonding 
Interactions from ab Initio Calculations, J. Am. Chem. Soc., 
111, 5149-5151 (1989)

ELECTROSTATIC INTERACTIONS

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U.  Koch  and  E.  Egert, An  Improved  Description  of  the 
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F. Colonna, E. Evleth and J. G. Angyan, Critical Analysis of 
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POLARIZATION EFFECTS

S.   Kuwajima  and   A.   Warshel,  Incorporating   Electric 
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J. W. Caldwell  and P. A. Kollman,  Structure and Properties 
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D. N. Bernardo, Y. Ding, K. Kroegh-Jespersen and R. M. Levy, 
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P.  T.  van  Duijnen  and M.  Swart,  Molecular  and  Atomic 
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J. M.  Stout and C. E.  Dykstra, A Distributed Model  of the 
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MACROSCOPIC TREATMENT OF SOLVENT

C. J. Cramer and D.  G. Truhlar, Continuum Solvation Models: 
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SURFACE AREA-BASED SOLVATION MODELS

D.  Eisenberg  and  A.  D. McLachlan,  Solvation  Energy  in 
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L.  Wesson and  D.  Eisenberg,  Atomic Solvation  Parameters 
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T.  Ooi,  M.  Oobatake,  G.  Nemethy  and  H.  A.  Scheraga, 
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J.  D.   Augspurger  and  H.  A.   Scheraga,  An  Efficient, 
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GENERALIZED BORN SOLVATION MODELS

W. C. Still, A. Tempczyk, R. C. Hawley and T. Hendrickson, A 
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D. Qiu, P. S. Shenkin, F.  P. Hollinger and W. C. Still, The 
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G. D. Hawkins, C. J.  Cramer and D. G. Truhlar, Parametrized 
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A. Onufriev, D. Bashford and D. A. Case, Modification of the 
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M.  Schaefer  and  M. Karplus,  A  Comprehensive  Analytical 
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M.   Schaefer,  C.   Bartels   and   M.  Karplus,   Solution 
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SUPERPOSITION OF COORDINATE SETS

S.   J.  Kearsley,   An  Algorithm   for  the   Simultaneous 
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S. C.  Nyburg, Some  Uses of a  Best Molecular  Fit Routine, 
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LOCATION OF TRANSITION STATES

R.  Czerminski   and  R.  Elber,  Reaction   Path  Study  of 
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R. S. Berry, H. L. Davis  and T. L. Beck, Finding Saddles on 
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S.  Fischer and  M. Karplus,  Conjugate Peak  Refinement: An 
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J. E. Sinclair and R. Fletcher, A New Method of Saddle-Point 
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R. Elber and  M. Karplus, A Method  for Determining Reaction 
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T. A.  Halgren and  W. N. Lipscomb,  The Synchronous-Transit 
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