[gmx-users] Problem with pressure form g_energy

Mikhail Stukan mstukan at slb.com
Sat Sep 18 13:57:32 CEST 2010


Dear gmx-users,

I have experienced the following problem with g_energy program. The problem is the same for at least three versions (3.3.4,  4.0.7 and 4.5.1). When I calculate pressure value (in NPT simulation) using g_energy I obtain the result (average value plus errors, drift etc.) and the instantaneous values of the pressure in energy.xvg file. But then, if I try to calculate the average value based on these instantaneous values I have significantly different number. I assume that the problem could be in precision (I run double precision version of GROMACS). Option  -dp in g_energy changes nothing, probably rounding is at some higher level than that. Is there any way to solve this issue? Should I also trust the result of g_energy rather than data in energy.xvg?  For the parameters that expose minor fluctuations (volume, density, temperature) this problem doesn't occur.

Thank you very much in advance,
Mikhail

=============================================
Dr Mikhail Stukan
Schlumberger Dhahran Carbonate Research Center,
Dhahran Techno Valley  - KFUPM,
P.O. Box 39011, Dammam / Doha Camp  31942,
Kingdom of Saudi Arabia
Tel: +966 3 331 0300 ext 6182
Fax:+966 3 330 0845
mstukan at slb.com<mailto:mstukan at slb.com>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://maillist.sys.kth.se/pipermail/gromacs.org_gmx-users/attachments/20100918/c5d27b0b/attachment.html>


More information about the gromacs.org_gmx-users mailing list