[MMTK] Does MMTK support negative AMBER PHASE values?

Konrad Hinsen hinsen at cnrs-orleans.fr
Mon Jun 4 08:15:48 UTC 2007


On 01.06.2007, at 09:51, Konrad Hinsen wrote:

> I just scanned the Amber parameter file and noticed that all the
> dihedral phase angles are either 0 or 180 degrees. Very probably
> nobody has ever tested different values, so there could well be a
> problem that has gone unnoticed. Perhaps the same could be said about
> the code in SANDER. I'll have to think about a suitable test case for
> individual energy terms.

There was indeed a bug in the evaluation of dihedral energies for  
phase angles other than 0 or pi. This has been fixed in the Mercurial  
repository, and it will be in the next release of course. For most  
users there is no need to hurry to get the fix, as none of the force  
fields that come with MMTK uses phase angles other than 0 or pi. This  
fix thus concerns only users who add their own force field parameters.

Konrad.
--
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Konrad Hinsen
Centre de Biophysique Moléculaire, CNRS Orléans
Synchrotron Soleil - Division Expériences
Saint Aubin - BP 48
91192 Gif sur Yvette Cedex, France
Tel. +33-1 69 35 97 15
E-Mail: hinsen at cnrs-orleans.fr
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