AMBER Archive (2004)

Subject: Re: AMBER: problems with dihedrals - extended information

From: Bill Ross (
Date: Mon Oct 18 2004 - 13:04:33 CDT

> It looks like something funny is going on
> when a second parameter file (in this case glycam_200a) is read in that
> changes the definitions of a previous one (in this case par99). Especially(?)
> when the number of terms for a given dihedral angle is different in the two
> files.

I remember working on this and thinking that the rules for
overriding torsion parameters seemed wrong. As far as I can
remember, the parameters are merged (keeping non-overridden
multiplicities) rather than having all the ones from the 1st
parm.dat/frcmod deleted before adding the new ones. This is
a user interface issue, and I favor the delete-all-multiplicities-
then-add-new-ones approach.

There could be a bug too :-)

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