AMBER Archive (2009)

Subject: Re: [AMBER] questions about RESP

From: Jeffrey (jeffry20072008_at_yahoo.cn)
Date: Mon Jul 20 2009 - 02:42:29 CDT

Dear Francois,

      Thanks very much for your information. I read that paper and make it clear of the different level of optimization. Another question is that why the structure should be optimized before calculating ESP? How about a structure near the mimimum point, but not at the real mimimum when calculating the ESP?

For large molecules, it is difficult to optimize the structure at 6-31G* level. So how about using a conformation obtained at a low level optimization?

Many thanks.

Jeffrey

--- 09年7月16日，周四, FyD <fyd_at_q4md-forcefieldtools.org> 写道：

发件人: FyD <fyd_at_q4md-forcefieldtools.org>
主题: Re: [AMBER] questions about RESP
收件人: "amber" <amber_at_ambermd.org>
日期: 2009年7月16日,周四,下午10:27

Dear Jeffrey,

>      If the optimization and ESP calculation are performed at  different level, e.g.  HF/3-21G for optimization and HF/6-31G* for  ESP calculation, how will it effect the fitted atomic charges?
> Are there any papers or materials discussing this topic?

You might find some information about that in
Hariharan, P. C.; Pople, J. A. Chem Phys Lett 1972, 16, 217.

regards, Francois

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