
               -----------------------------------------------
               PARAMS Directory for the TINKER Program Package
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      This directory contains the force field parameter sets distributed
      with the TINKER package, implementing a selection of widely-used
      literature force fields as well as the TINKER force field now
      under development 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. Please inform
      the TINKER developers of any discrepancies. A brief description of
      each parameter set is provided below:

      amber      AMBER-94 parameters for proteins and nucleic acids.
                 Note that N- and C-terminal amino acid charges differ
                 slightly from the authentic charge values. For these
                 terminal residues some charge is redistributed to or
                 from the alpha carbon atom; the total magnitude of the
                 redistribution is less than 0.01 e- in most cases. The
                 file reproduces the authentic parm94 set; torsional
                 parameter changes for parm96 are noted in that section
                 of the file.

      charmm     CHARMM27 parameters for proteins and heme. Most of the
                 nucleic acid, lipid and small model compound parameters
                 are not yet implemented.

      dudek      Protein-only parameters for the TINKER force field
                 with multipole values of Dudek and Ponder. The current
                 file contains all the multipole values from the 1995
                 JCC paper. These values are superceeded by the full
                 TINKER force field still under development.

      emr        Reduced EMR model of Pappu, Schneller and Weaver.
                 Only a few residue types have been implemented.

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

      hoch       Simple NMR-NOE force field of Hoch and Stern.

      merck      Preliminary MMFF vdw parameters from Halgren.

      mm2        Full MM2(1991) parameters including pi-systems. The
                 anomeric and electronegativity correction terms are
                 not implemented.

      mm3        Full MM3(2000) parameters including pi-systems. The
                 directional hydrogen bonding and electronegativity
                 bond length correction terms are implemented, but
                 the anomeric and Bohlmann correction terms are not
                 implemented.

      mm3pro     Protein-only version of the MM3 parameters.

      mmff       MMFF94 parameters (in preparation).

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

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

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

      smooth     Parameters for use with the TINKER potential energy
                 smoothing methods. Largely adapted largely from
                 OPLS-UA with modifications to the vdw and improper
                 torsion terms.

      smoothaa   Similar to SMOOTH, but based on OPLS-AA parameters.

      tinker     Preliminary TINKER protein force field based on the
                 use of polarizable atomic multipole electrostatics.

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

