[gmx-users] Pressure from Ke and Virial from .edr

Hardy, Adam ah259 at hw.ac.uk
Thu Aug 13 16:23:04 CEST 2015

Dear All,

As part of my work I need to recalculate the pressure from the kinetic energy and virial.

I start with the equation (2/V)(Ke – Vir).

The units given for the virial and kinetic energy (as taken from the .edr file) are given in kJ/mol so when I calculate the values of the pressure components and convert units I’m left with a pressure in Bar/mol (kJ/m^3 mol -> 10^3 Pa/mol -> 10^-2 Bar/mol). My initial thought was to multiply by Avogadro’s number but this gives me a number that is~750 times too large so clearly I’m missing something. Where am I going wrong?

Many thanks,


Adam Hardy
PhD Student
School of Engineering and Physical Sciences
Heriot Watt University
Edinburgh, EH14 4AS
Phone: +441314513074
ah259 at hw.ac.uk<mailto:ah259 at hw.ac.uk>

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