Subject: Re: CCL:calculation of stress with SHAKE/RATTLE

From: Konrad Hinsen <[email-masked]>
Date: Fri, 10 Aug 2001 17:59:13 +0200

> how does one calculate the stresses when constraint dynamics is used? or
> is there a way to seperate the constraint forces as two equal and opposite
> forces so that the stress calculation is simple?(am using the RATTLE
> routine provided in Allen & Tildesley book)

If you have only pair distance constraints, then the constraint forces
can be decomposed in such a way. In fact, just look at the derivation
of SHAKE and RATTLE: the constraint forces are written as a Lagrange
multiplier times the pair distance. The Lagrange multipliers can be
calculated explicitly during the SHAKE/RATTLE iterations.
-- 
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