Subject: RE: Qeq & others charge equilibration method

From: "Smith JA (Jack)" <[email-masked]>
Date: Fri, 16 Jan 1998 15:54:57 -0500

> I currently need a very fast method to estimate the molecular
> electrostatic potential outside de Van der Waals surface, preferably
> avoiding QM calculations, and turn to empirical charge equilibrations
> methods. Finally I consider using the QEq scheme, but maybe I could
> benefit from the experience of some of us, especially if s.O. already
> studied MEP built from QEq charges ??
> 
A simple idea I've been toying with is the use of Rappe's QEq scheme
(perhaps coupled with Landis' VALBOND scheme) together with a
variationally derived analytical Thomas-Fermi expression for the charge
density of charged atoms.  This generates a very quick, crude, but
surprisingly good electron density (a superposition of charged atom
densities) and a full electrostatic potential (in analytical form)
corresponding to the QEq charges.  It's fast enough to perform at an MD
timescale.

- Jack

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 Jack A. Smith             ||
 Union Carbide             || Phone:  (304) 747-5797
 Catalyst Skill Center     || FAX:    (304) 747-4672
 P.O. Box 8361             || 
 S. Charleston, WV  25303  || [email-masked]
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