Re: force fields

From: Mihaly Mezei <>
Date: Wed 7 Mar 2001 14:44:26 -0500

> All these forcefields
> are empirical approximations to the underlying quantummechanical potential
> energy hypersurface.
Just two small comments:

The FF parameters, don't just approximate the underlying quantummechanical
energies, they generally include multibody (e.g., polarization)
contributions in an average way, so I would add that they approximate also
the underlying statistical mechanics as well.

As for the mixing of FF parameters, one additional indicator of danger is
the fact that fitting the coeeficients of the usual 12-6-1 potential
generally results in a very ill-conditioned matrix, indicating that
essentially the same quality of fit can be obtained with rather different

Mihaly Mezei,

Dept. of Physiology & Biophysics, Mount Sinai School of Medicine
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Received on Wed Mar 07 2001 - 11:44:26 PST
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