I try to use the compute stress/atom command. Its syntax is:
compute ID group-ID stress/atom temp-ID keyword ...
In the manual, it's said that the temp-ID argument can be used to affect the per-atom velocities used in the kinetic energy contribution to the total stress. If the kinetic energy is *not included* in the stress, than the temperature compute is not used and can be specified as *NULL*. If the kinetic energy *is included* and you wish to use atom velocities as-is, then temp-ID can also be specified as *NULL*.
I'm confused by this paragraph. From this paragraph, I don't know whether per-atom velocities are used when I set temp-ID to be NULL in this command.
In my simulation, group-ID is not 'all', and I want to include the kinetic energy in the compute, i.e. use the per-atom velocities in the specified group, should I use NULL or thermo_temp as temp-ID in this command?