Date: Fri, 28 Jan 2000 15:52:40 -0500
From: "Bayly, Chris"
Subject: RE: RESP question

Because the nitro and trifluoromethyl groups are polar, they should be
equivalenced at the first stage. Doing so at the second stage would cause a
marked deterioration in the quality of the fit around the important polar
areas of these groups.

Second stage equivalencing is only for atoms describing non-polar areas of
the electrostatic potential.

Christopher


> ----------
> To: amber@cgl.ucsf.edu
> Subject: RESP question
>
> I have a question regarding RESP fitting of a small molecule in which heavy
> atoms are to have equivalent charges. I have two examples of this in one
> molecule, e.g. a nitro group in which the oxygens are to be equivalent and a
> trifluoromethyl group where the fluorines are to be equivalent.

> My question is at which stage of a two stage fitting should these atoms be
> made equivalent?
>