[gmx-users] Enthalpy Confusion

David van der Spoel spoel at xray.bmc.uu.se
Tue Jun 11 20:30:00 CEST 2013

On 2013-06-11 20:09, Jeffery Perkins wrote:
> This may just be me not understanding what I'm looking at, but I'm trying to
> get the Enthalpy of a simple test system of LJ fluid, running version 4.5.4
> initially I've tried using the enthalpy option in g_energy but I noticed
> that if i compare that value to H=U+pV using either the average  or the
> instantaneous values from g_energy switched over to SI so that there is no
> issue there, the results are different (manual calculation is around 2x the
> g_energy result).
> So the question is, what am I overlooking in the analysis of the data i
> have?
The calculation is done inside mdrun and it provides
H = Etot + pV

where p is the applied pressure (typically 1 bar).
Is this the same that you did?
> --
> View this message in context: http://gromacs.5086.x6.nabble.com/Enthalpy-Confusion-tp5009053.html
> Sent from the GROMACS Users Forum mailing list archive at Nabble.com.

David van der Spoel, Ph.D., Professor of Biology
Dept. of Cell & Molec. Biol., Uppsala University.
Box 596, 75124 Uppsala, Sweden. Phone:	+46184714205.
spoel at xray.bmc.uu.se    http://folding.bmc.uu.se

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