From: Juan Alfredo Freites (jfreites_at_ea.nacs.uci.edu)
Date: Sat Feb 28 2004 - 20:18:51 CST
On Sat, 28 Feb 2004, Sichun Yang wrote:
>
> Thank you for your explanation, Jerome.
> However, How can I understand a negative GPRESSURE?
>
The usual convention for the diagonal elements of the pressure tensor is
positive for compression. If you're simulating a bulk system, i.e.
if you're in hydrostatic conditions you want to get the scalar pressure which is
one third of the trace of the pressure tensor. In a constant pressure
simulations, the average of that quantity should give you back the
requested value.
Make sure that you check here
http://www.ks.uiuc.edu/Research/namd/current/ug/node14.html#SECTION00062200000000000000
to understand the difference between namd's group and atomic pressure
tensor calculations and their partial cumulated averages PRESSAVG and
GPRESSAVG.
-- J. Alfredo Freites Department of Physics University of California, Irvine Irvine, CA 92697-4575 (949) 824-9921
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