AMBER Archive (2002)

Subject: Re: charges

From: David Case (case_at_scripps.edu)
Date: Thu May 23 2002 - 15:54:38 CDT

On Thu, May 23, 2002, Marcela Madrid wrote:
>
> I run Gaussian on a small molecule with the iop(6/33=2) keyword,
> and then I run antechamber to get the RESP charges:
>
> antechamber -i gauss.out -fo ac -fi gout -c resp -nc 2 -o anteresp.out
>
> This did not work because it did not know what kind of atom Pt was. So I
> edited
> ANTECHAMBER_RESP.AC and run each step separately (espgen, respgen, resp,
> bcctype,
> bcc).
>
> My question is:
> How can I know if the charges that I am getting make sense? They are
> very different
> from the Mulliken charges, and I am getting a negative charge for Pt,
> while I expected a positive charge. Thanks! Marcela
>

I'm not sure what one should expect from RESP for this situation. Note that
charges for atoms that are "buried" (such as a Pt that is surrounded by
ligands) the charge on the central atom is not well-determined.

You might want to just set the "MK" (or similar) option in Gaussian, and
get the ESP (without the "R") charges. This is probably fine, since RESP
was never calibrated for metal complexes anyway. And since it runs entirely
within Gaussian, you are insulated from any problems with the resp codes.
Then compare the results with what you got.

...good luck...dac 

-- 

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David A. Case                     |  e-mail:      case_at_scripps.edu
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