If you are computing enthaply in the NPT ensemble, P is constant, and is the applied pressure.
The "pressure" quantity calculated from the KE and the virial is not the pressure. It is a quantity that when averaged over time is equal the pressure. Only the average is meaningful macroscopically. If you are computing enthalpy in another ensemble (which is possible, though it may be harder to interpret) then you would use the average pressure from this quantity. On Tue, Jun 11, 2013 at 3:08 PM, Jeffery Perkins <jeffery.perk...@ufv.ca> wrote: > that's what i thought, and what i tried to do, my pressure is a bit higher > then that, we want a Lennard-Jones liquid so it's running at 1000+ bar, and > while I agree that gromacs is giving H as Etot + pV it appears that when i > calculate pV i get a different value from what g_energy returns for it I did > p in Pa, V in m^3, as the whole box, to get J of energy, and then multiply > by 6.02E23 to get J/mol of my box, and then convert down to kJ/mol to be the > same units as g_energy. > > When you say the applied pressure you mean that p = ref_p? or the calculated > pressure from the virial and Ke? > > Thanks for the help, > > Jeffery > > > > -- > View this message in context: > http://gromacs.5086.x6.nabble.com/Enthalpy-Confusion-tp5009053p5009058.html > Sent from the GROMACS Users Forum mailing list archive at Nabble.com. > -- > gmx-users mailing list gmx-users@gromacs.org > http://lists.gromacs.org/mailman/listinfo/gmx-users > * Please search the archive at > http://www.gromacs.org/Support/Mailing_Lists/Search before posting! > * Please don't post (un)subscribe requests to the list. Use the > www interface or send it to gmx-users-requ...@gromacs.org. > * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists -- gmx-users mailing list gmx-users@gromacs.org http://lists.gromacs.org/mailman/listinfo/gmx-users * Please search the archive at http://www.gromacs.org/Support/Mailing_Lists/Search before posting! * Please don't post (un)subscribe requests to the list. Use the www interface or send it to gmx-users-requ...@gromacs.org. * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists
