[lammps-users] compute stress/atom command

I can tell you that if this is what you’re trying to do, what you were listing in your script will NOT work. First, your formulas are absolutely wrong—please consult one of the many papers that talk about how to do surface tension measurements using MD for the correct forms of the equations.

Secondly, the method you’d like to try is also guaranteed to fail, because the stress/atom measurement does not include long-range electrostatics. Normally, this might not be such a big deal, but for water, the contributions from electrostatics cannot be ignored.

Take a look at Israelachvili’s text on Intermolecular Forces to see alternate methods that will allow you to calculate the liquid-liquid surface tension.


Dear Ahmed Ismael

As you can see in the attached paper the interracial tension is calculated for a oil/water/Surfactant system using LAMMPS. I followed their formula for interfacial tension. Do you think their formula is false?
Would you please tell me your other suggestion?




Jang etal 2004.pdf (250 KB)

Their formulas appear to be fine; I just don’t see where your implementation is the same as theirs.

But as I said, regardless of whether or not you get the formula right, the result will be wrong, because the lack of long-range electrostatics will affect the answers.

As for the alternate method, as I said in my previous message: consult Israelachvili’s book, or look at papers where droplets are placed on surfaces.