dboc(1)

NAME
dboc - Diagonal Born-Oppenheimer Correction using HF and CI wave functions.

DESCRIPTION

The program dboc computes Diagonal Born-Oppenheimer Correction (DBOC) using HF and CI wave functions.

REFERENCES

"Cartesian" DBOC formula (aka Born-Handy-Pulay formula):

1.  N. C. Handy, J. Yamaguchi, and H. F. Schaefer, J. Chem. Phys. 84, 4481 (1986).

Justification for the "Cartesian" DBOC formula:

1.  W. Kutzelnigg, Mol. Phys. 90, 909 (1997).

Finite-difference formulation of DBOC at CI level

1.  E. F. Valeev and C. D. Sherrill, J. Chem. Phys. 118, 3921 (2003).

INPUT FORMAT

The following keywords are valid:

WFN = string
    Specifies the type of wave function desired. The only valid entries at the present are SCF and DETCI. There is no default.

REFERENCE = string
    Specifies the type of orbitals used for the single-determinant reference function. Valid choices are RHF, ROHF, and UHF. There is no default.

PRINT = integer
    Determines the verbosity of the output. A value of 0 (the default) specifies minimal printing.

:DBOC:DISPLACEMENT = real
    Determines the finite difference step (in a.u.). The default is 0.0005 a.u.

:DBOC:ISOTOPES = string_vector
    Specifies which isotope to use for each atom. Each string should specify an isotope label as defined in include/masses.h. By default, most abundant isotopes are used for each element.

:DBOC:COORDS = vector
    This keyword should only be used by advanced users who are familiar with how DBOC is evaluated by finite differences. The keyword may be used to specify the cartesian nuclear coordinates to use in the sum expression for DBOC and their respective coefficients. dboc doesn't currently use symmetry to reduce the number of displacements, however, all computations are performed in the highest Abelian point group. Hence this keyword can be used to reduce the number of displacements and/or to specify the exact orbital occupations for specific displcements in case the occupation guess produced by cscf is not correct. The value for this keyword is an array of 2 element vectors. The first element of each vector is the index of the cartesian coordinate which to include into the sum and the second element is a real coefficient for the respective term in the DBOC expression. Indices are C-style, i.e. from 0 to 3*natom-1. By default derivative along each Cartesian coordinate comes into DBOC expression with coefficient 1.0.