Re: [AMBER] Problem with CG minimization in implicit solvent

From: David A Case <>
Date: Thu, 11 Mar 2021 16:18:35 -0500

On Thu, Mar 11, 2021, Adrian Roitberg wrote:

>> After the first initial steps using steepest descent, CG energies and
>> forces exhibited frequent jumps of several orders of magnitude as the
>> minimization progressed.

But it looks like you are still getting lower energies.

FWIW: the conjugate gradient code in runmin is about the oldest code
around in Amber: I think it even precedes molecular dynamics. The entire
runmin subroutine will be gone from future releases of sander, but not for
AmberTools21. I don't know how we will handle the situation for pmemd.cuda.

>> If the xmin minimizer is used with PRCG then the issue disappears.

Indeed. Anyone who wants a good minimization should use xmin; just be sure
to turn off SHAKE. (The latter is done automatically in development codes.)


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Received on Thu Mar 11 2021 - 13:30:02 PST
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