[gmx-users] g_energy and pressure values

[McMullen, Roger L]

Greetings all.

I have a fatty acid monolayer (64 fatty acids) on H2O with a packing density
of 20 A^2/molecule.  We are trying to simulate a Langmuir trough experiment
in which lateral pressure is monitored as a function of the molecular
packing density (perimeter area).  As a first approximation, we would like
to keep the volume of the box constant in order to maintain a packing
density of 20 A^2/molecule and monitor the corresponding lateral pressure.
We have run the simulations and are trying to use g_energy to calculated the
pressure.  g_energy provides various pressures: Pres-XX, Pres-XY, Pres-XZ,
Pres-YX, Pres-YY, Pres-YZ, Pres-ZX, Pres-ZY, and Pres-ZZ.  What do these
pressures correspond to?  Does any one have any experience working with such
a system?

Thank you,
Roger McMullen