[gmx-users] Pressure of an energy minimized system

[Rakesh Sharan]

Dear all,

I have a question regarding computation of pressure of an energy minimized
(using steepest decent) system. I would expect that the pressure of an
energy minimized system should have contribution only from the virial part
of the pressure expression (as there is no temperature). However, when I am
computing pressure using g_energy, the pressure (P_tot) and pressure
computed from virial (P_vir = (-1/3Vol)*(Vir_xx+Vir_yy+Vir_z)/3)) are
significantly different and P_tot is exactly six times P_vir. I am not able
to understand the origin of this discrepancy. I would highly appreciate
comments/suggestions from this forum. I would also very much appreciate any
alternate suggestion for computing pressure of energy minimized structures.

Thanks very much!

Best,
Rakesh

----------------------------------------------------
Rakesh S. Singh, Ph.D.
Postdoctoral Research Associate,
Department of Chemical & Biological Engineering,
Princeton University,
Princeton, NJ 08544