[gmx-users] Pressure of an energy minimized system

[Mark Abraham]

Hi,

We discussed this recently at
https://mailman-1.sys.kth.se/pipermail/gromacs.org_gmx-developers/2015-October/008710.html.
Whether it correctly computes the well defined quantity isn't known;
neither does anybody know of a good use for it!

Mark

On Tue, 8 Mar 2016 14:31 Rakesh Sharan <rs11chembhu at gmail.com> wrote:

> 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
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