AMBER Archive (2008)

Subject: Re: AMBER: Question about resp charges for a charged molecule...

From: FyD (
Date: Fri Oct 10 2008 - 08:37:48 CDT

Quoting Alberto Sergio Garay <>:

> My name is Sergio Garay and I have some doubt about some of my results.
> I have obtained the resp charges of my molecule using gamess' ESP grid.

Using HF/6-31G* GAMESS and Gaussian provide the same ESP grid
(Connolly surface or CHELPG algo.) _if_ the molecular orientation of
the structure used in MEP computation are the same.

> I employed 6-31G* basis set in HF calculus. My molecule is charged +1
> and I have obtained partial charges on some of the atoms very large.
> For instance, I have a +5 charge on one of my atoms. Is this
> reasonably?

You clearly have a problem.

> Could anyone give me any clue about how to parametrize the
> charge of a molecule as mine (molecule with a positive charge).

You could try to run R.E.D.
You have to prepare a p2n file...

regards, Francois

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