Dear Friends
In Manual you can see that compute pressure specified group command must be “all”. If we have some local groups in the simulation box (for example in left side of the box includes LEFT group and in the right of the box includes RIGTH group). Is it possible to change the names of groups (LEFT and RIGHT) to all and use compute pressure for each group? for example is it possible to change RIGHT to “all” using variable command that it’s style is “string”?
Would you give me any suggestion that you know?
Thanks alot for your time and attention.
Regards
Saly
You can use the compute stress/atom command to get
the stress (pressure) for individual atoms. You can sum
them over the atoms in a group. But it does not make
sense to compute the global pressure on a subset of
atoms in the system. It's not a well-defined quantity.
Steve
Dear Steve
As I said in my previous emails there is water n my system and I used kspace style command, therefore I can not use compute stress/atom. But If with compute pressure I can calculate local pressures I can obtain my goal.
Do you have any other suggestion?
Regards
Saly
Dear Steve
As I said in my previous emails there is water n my system and I used
kspace style command, therefore I can not use compute stress/atom. But
If with compute pressure I can calculate local pressures I can obtain
my goal.
no, you cannot. why do you think there is the requirement
for this compute to only operate on the group "all" (which
is predefined to contain all atoms)?
don't see that you are turning in circles?
there is no way to beat the laws of physics by
input file trickery.
as per our previous discussion, you either
have to use the global pressure tensor
or do some approximation to get your result.
axel.