AMBER Archive (2002)

Subject: Partial charge generation RESP/antechamber

From: James W. Caldwell (caldwell_at_heimdal.compchem.ucsf.edu)
Date: Mon Sep 30 2002 - 17:27:37 CDT

Please note the following regarding Gaussian98 and
partial charge generation for Amber uses:

The FINAL set of molecular properties in a G98 output
is the one to use for charge generation.

If you run a single point, that is the only one.
If you run a geomertry opt, Gaussian does a property
analysis on the INITIAL geometry and then again on
the FINAL geometry.

The reason I'm bringing this up is that the script
distributed with Amber7 and on the Web site for a
standalone RESP setup assumes a SINGLE point G98 run.

On the other hand, Antechamber is programed to look for
the last property set and so it doesn't matter if you
feed it a single point or optmization run.

To clarify the Antechamber G98 input in the sample run:

 #HF/6-31G* SCF=tight Test Pop=MK iop(6/33=2) iop(6/42=6) opt

  HF/6-31G* calculation type and basis set

  SCF=tight normally G98 does optimizations at a
              reduced convergence level (a single
              point run is "tight" by default)

  Test extra output

  Pop=MK Do a Merz-Kollman ESP fit to get partial charges

  iop(6/33=2) Output the ESP data to the standard output file
              for Gaussian.

  iop(6/42=6) calculate 6 points per unit area for the ESP, the
              default is 1 (I have no idea what the unit area
              actually is)

  opt do a geometry vs. energy optimization of the input
              coordinates. 

-- 

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James W. Caldwell                         (voice) 415-476-8603
Department of Pharmaceutical Chemistry    (fax)   415-502-1411  
Mail Stop 0446                            (email) caldwell_at_heimdal.ucsf.edu
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University of California                  
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