Calculating pressure in a specified group of atoms

Hello,

As stated in the title I would like to calculate pressure for a predefined group of atoms not for whole system. Is there a simple way to do that?

Regards,
B. Czerwinski

Hello,

As stated in the title I would like to calculate pressure for a
predefined group of atoms not for whole system. Is there a simple way to
do that?

no. you can compute (and sum) the per atom stress for your group, but
to turn this into a pressure, you also need the corresponding volume.
for the whole system (under PBC), this is easy to determined, but for
a group of atom it is not a very well defined quantity. there are
different ways to try to approximate it which have been applied with
different degrees of success.

this topic has been discussed a lot on this mailing list before and i
suggest you dig through the mailing list archives to see what people
have come up with.

axel.

Axel is referring to the compute stress/atom command.
It’s doc page discusses the volume issue.

Steve