Subject: Re: CCL:SHAKE problem.

From: Rick Venable <rvenable(at)pollux.cber.nih.gov>
Date: Tue, 22 Jul 2003 11:52:47 -0400

On Mon, 21 Jul 2003, Michael Chen wrote:
>    I ran a multi-processor job in use of SHAKE, and I got tons of
> bizzar messages like this:
>
>  ERROR in SHAKEA. Contraints spanning parallel partition ignored.
>
>    Would someone please tell me what was going on? Was this because of
> hardware things or software things? My CHARMM still kept running, but
> those messages were so annoying.

It means you are attempting to apply SHAKE to bonds between heavy atoms,
e.g. C-C bonds, which is a problem for parallel usage.  The constraint
is not applied (ignored) for any case where the 2 atoms have been
partitioned onto separate processors.

A more typical usage of SHAKE is

SHAKE BONH PARAM

where only bonds to H atoms are constrained (to their parameter length);
the atom partioning scheme always keeps H atoms in the same partition as
the heavy atom they are bonded to, so the above error message should not
occur.

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Rick Venable           29/500
FDA/CBER/OVRR Biophysics Lab
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(301) 496-1905   Rick_Venable(at)nih.gov
ALT email:  rvenable(at)speakeasy.org
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