AMBER Archive (2005)

Subject: Re: AMBER: EWALD and belly not strictly correct

From: darden (darden_at_gamera.niehs.nih.gov)
Date: Wed Feb 16 2005 - 11:08:31 CST


dear julie
the problem is that the interactions calculated using the typical nonbond
list can be filtered if one or both atoms are frozen i.e. the nonbond
energy and force for such a pair are not calculated---BUT there is no way
to efficiently do such a filter in reciprocal space---so the reciprocal
part of the interaction for that pairr is calculated---the net result is a
slightly incorrect calculation---in practice its not too bad--but its
probably better to use restraints instead of belly option if you can
Tom

On Wed, 16 Feb 2005, Stern, Julie wrote:

> Hello,
> I'm freezing atoms using the belly option and running a minimization.
> The
> min.out file contained this warning:
>
> Warning: Although EWALD will work with belly
> (for equilibration), it is not strictly correct!
>
> So, what does this mean? Why isn't it correct?
>
>
> Thanks.
>
> --Julie
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