Author: Gilbert Hangartner, Universität Freiburg, Switzerland
Purpose: Reads the Formatted Checkpoint file of Gaussian
and creates a DALTON.HES file with Hessian and Atomic coordinates
as well as a dummy MOLECULE.INP file.
Commandline: FChk2HES [-n] [filename]
-n does not read and write geometry; filename is optional, default is
"Test.FChk" .
Comments: The Gaussian checkpointfile "Test.FChk" is created with the keyword "FormCheck=ForceCart", and where the keyword "NoSymm" has been specified
If symmetry is used: Hessian will be in standard(Gaussian) orientation,
but geometry will be in input orientation. So do not use the
MOLECULE.INP file from this utility,
neither the coordinates in the end of DALTON.HES.
Use either the standard-orientation from Gaussian outputfile, or
use the converted checkpointfile (created with the command
"formchk checkpointfilename convertedfilename") as an input for
this program. Anyway, this will not lead to the geometry you
specified in the input, and the Hessian will be incompatible with the
calculation you want to do in DALTON. (IF THIS WAS ALREADY CARRIED
OUT AT THE INPUT ORIENTATION ...)
THE ONLY WAY TO GET THE GEOMETRY ORIENTATION YOU WANT IS TO TURN OFF SYMMETRY. THEN, BOTH THE HESSIAN AND THE GEOMETRY IN THE TEST.FCHK FILE ARE IN THE INPUT ORIENTATION, AND EVERTHING IS FINE.
THE PROGRAM HAS BEEN MADE FOR THE PURPOSE OF BEING USED IN VCD OR VROA CALCULATIONS WHERE IT MAY BE OF INTEREST TO COMPARE PREDICTED SPECTRA OBTAINED FROM SCF LONDON ORBITAL INVARIANTS/AATS WITH A MP2 OR DFT FORCE FIELD.