[gmx-users] surface tension units

Ashish Gupta agupta at che.ufl.edu
Wed Jan 26 18:50:28 CET 2005

Hello gmx-users:

  I am trying to use g_energy to calculate surface tension. I use
Pressure(xx) Pressure(yy) Pressure(zz) to calculate surface tension using
the formula :
surface_tension = Lz/n * {Pzz - (Pxx+Pyy)/2}

The units of surface tension from this calculation is KJ/(mol-nm2) . What
does mol signify here. Is it just a constant for ease of operation.
I also found that g_energy has -nmol option with it. When I used this option
my values of energies changed but not pressure. I shall be glad if someone
can help me better interpret the unit of KJ/mol.
I am using coarse grained model in which a single bead may represents 4
methyl groups or other group of atoms. So should I be more careful while
using g_energy.

Thanks for any help,
Ashish Gupta

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