Enthalpy calculation from NPT simulation

From: sudipta (sudipta.mml_at_gmail.com)
Date: Wed Aug 11 2010 - 13:54:16 CDT

Hi All,

        I have ran a NPT simulation for a liquid water system (TIP3P) model
and want to calculate enthalpy of the system at that temperature. How shall
I proceed? I have used lagevin dynamics for temperature and pressure
control. Actually the conserved quantity in NPT simulation is enthalpy. In
the output file of the simulation it provides kinetic energy and potential
energy of the system. But the kinetic and potential energy of extended part
is not given their. How shall I extract them from a output file.

If I calculate enthalpy as KE+PE+Pressure(ext)XdeltaV, then is it logical.
The Pressure(ext) is the external pressure and deltaV is the volume change
that given in .xst file.

Any suggestion will be highly appreciated.

Thanks and regards

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