dboc(1) 																   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:DISP_PER_COORD = integer
	      Determines the number of displacements for each coordinate. Set it to 2 to compute DBOC with standard accuracy  (enough  significant
	      digits  for  up  to  second derivatives; DBOC accurate to square of displacement size), and 4 to compute DBOC with improved accuracy
	      (DBOC accurate to the fourth power of displacement size).  The default is 2.

       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, their respective	coefficients,  and
	      whether  they  are symmetric or nonsymmetric with respect displacements.	dboc can use symmetry to minimize the number of wave func-
	      tion computations.  Hence this keyword need only be used for diagnostic purposes or when displacements along  different  coordinates
	      need  to	be  run separately (e.g.  require different occupation vectors).  The value for this keyword is an array of 3 element vec-
	      tors. The first element of each vector is the index of the cartesian coordinate which to include into the sum. The second element is
	      a  real coefficient for the respective term in the DBOC expression. The third element is a string that can take two values, symm and
	      nonsymm, which indicate that the coordinate is symmetric or nonsymmetric with respect to displacements, respectively.   Indices  are
	      C-style, i.e. from 0 to 3*natom-1.

								  30 August, 2003							   dboc(1)