AMBER: Harmonic constraints

From: Johan Qvist <>
Date: Fri, 7 Sep 2007 16:43:57 +0200

Dear Amber community,
I am using Sander (under Amber 8) and the ff99 forcefield to run MD
simulations with cartesian hamronic restraints on some atoms, (i.e. using
NTR = 1). Now my question is simply if the specified force constant enters
as k/2*(x - x0)^2, as commonly definied, or as k*(x-x0)^2? The question
might be stupid but while I was reading the manual I got the impression that
the latter could be the case as all forcefield references in the manual are
to this form.

It would be great if someone could dispell my doubts.

Best regards /Johan Qvist

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Received on Sun Sep 09 2007 - 06:07:31 PDT
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