Dear all,

I would like to know how to apply a pressure difference to a group of atoms?

Suppose I have a water slab which is periodic in x and y dimension, now I’d

like to apply, say, 2 atm pressure to the slab along z axis in the positive direction,

while apply, 1 atm pressure to the slab along z axis in the negative direction.

I’m now using addforce to the atom to mimic a net pressure difference,

but forces applied to each atoms are the same which seemed not consistent with

what should be in the real case.

Any suggestion is highly appreciated~

Chen Chen