Re: Urey-Bradley term and VDW energy

From: Mark Abraham (
Date: Wed Oct 25 2006 - 22:50:33 CDT

Hyonseok Hwang wrote:
> Dear all,
> I'm wondering if the Urey-Bradley term is associated with VDW energy?
> That is, if I change some of Urey-Bradley parameters, does it affect the
> VDW energy?

No. A U-B term is between two atoms that are bonded to a common atom.
VDW terms are between two arbitrary atoms, and are usually excluded for
atoms that are bonded, or share a bond with a common atom. 1,4-VDW terms
vary a bit.

Please see your nearest textbook for details, or the paper that
describes your force field. :-)


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