AMBER Archive (2005)

Subject: Re: AMBER: Antechamber/Divcon assigned charges

From: David A. Case (case_at_scripps.edu)
Date: Thu Mar 03 2005 - 23:17:13 CST

On Thu, Mar 03, 2005, Marc Christensen wrote:
> I have a question regarding Antechamber and Divcon.
>
> If one looks at the tutorial for simulating Sustiva using the General Amber
> Force Field, the Divcon program is called to optimize the geometry then
> assign Partial Mulliken, Partial CM1, and Partial CM2 charges (at least
> this is what I gather from the Divcon.out file). However; when looking at
> the charges that end up in the Sustiva.prepin file they are different from
> the ones in the Divcon.out file.
>

If you specify "-c cm2" to antechamber, you should get the CM2 charges, as
extracted from divcon. If you specify "-c bcc" (which I think is what the
tutorial does) you will get the "AM1-BCC" charges, which start from Mulliken
charges and add bond increment corrections. The "bcc" method is described
here:

%A A. Jakalian
%A B.L. Bush
%A D.B. Jack
%A C.I. Bayly
%T Fast, Efficient Generation of High-Quality Atomic Charges. AM1-BCC
Model: I. Method
%J J. Comput. Chem.
%V 21
%P 132-146
%D 2000

%A A. Jakalian
%A D.B. Jack
%A C.I. Bayly
%T Fast, Efficient Generation of High-Quality Atomic Charges. AM1-BCC Model:
%II. Parameterization and Validation
%J J. Comput. Chem.
%V 23
%P 1623-1641
%D 2002

I must admit that the Users' Manual is not very clear on this point.

...dac
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