# [gmx-developers] pV term calculated incorrectly

Michael Shirts michael.shirts at virginia.edu
Thu Nov 26 04:11:28 CET 2009

I noticed that the pV term stored in the mdebin when a NPT simulation
is performed is calculated incorrectly -- it uses the instantaneous
pressure, when it should be using the applied pressure.  dU = pdV, so
with constant p, U = \int p dV = p \int dV = pV

I've written a fix (with full generality for arbitrary stress/strain),
but have realized I'm not exactly sure which branches I should be
checking into, and can't figure out exactly which git command I should
be using from the gromacs web page.  Any hints?

Best,
Michael