Re: [AMBER] Regarding Force constants from Mopac

From: David A Case <>
Date: Thu, 12 Jul 2018 08:34:37 -0400

On Thu, Jul 12, 2018, Devashish_Das wrote:
> I want to know if it is possible to use mopac generated force constants
> (bond, angle, dihedral) which is generated in millidyne/ in frcmod.
> (antechamber gives segmentation fault)

Can you be more specific? I don't understand your question,
or what you are asking antechamber to do.

Generally, you can edit a frcmod file by hand to change the parameters
if you wish to do so. Note that "force constants" generated by quantum
chemistry programs differ from those used in force fields by more than
just a unit change: bond and angles also differ by a factor of 1/2, and
dihedral terms in force fields generally have a quite different
functional form than is used in (most) quantum chemistry programs. So,
be sure that your hand-modified force field is giving results that are
what you desire.


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Received on Thu Jul 12 2018 - 06:00:03 PDT
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