AMBER: more vlimit exceeded problems...

From: Linda Prengaman <>
Date: Tue, 6 Apr 2004 22:22:44 -0400 (EDT)

I am running thermodynamic integration for a small system solvated in
water. I am running the calculations concurrently for 5 clambda values.
The runs for the first 3 lambdas were fine, but the 4th and 5th lambda runs
returned a "vlimit exceeded" error after just a few steps and "nan" values
for numbers. I am using an exact copy of my sander input file for all of
the other lambda values, except with of course the lambda value changed,
so I don't understand why my system is not working for this value. I have
performed minimization and gotten a good value for energy and the other MD
calculations I have done for this system were also stable. I have fixed
my problem by changing my dt parameter from 1 fs to 0.5 fs, but I know
this is not a practical fix because it doubles the time of my runs from 3
hours to 6 or 7. Please email me if anyone out there has abetter solution
to this problem.
Thank you,
Linda Prengaman

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Received on Wed Apr 07 2004 - 03:53:00 PDT
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