Restricted region

Dear all,

I was wondering if Lammps allows the possibility of calculating the pair-wise force for a particular interaction for each atom within a defined region.

To make myself more clear I will give the example of a binary LJ system with interactions 1-1 2-2 and 1-2.

Would it be possible to calculate the force on each particle within a defined region (For example a user defined cube which is a small portion of the entire simulation cell) for only the 1-2 interaction?

Many thanks in advance, Jeff.

The dump command will dump forces on atoms. You can define a group
to be a region and the dump command takes a group as an argument.
The dump_modify region command also lets you specify a region.

If the total force on an atom is not what you want, then you cannot get
at some sub-component (like 1-2 interactions only) with a normal LAMMPS run.

However if you have dump snapshots on the timesteps you want, you
can use the new rerun command to read them back in, and compute forces
for those snapshots. With a new dump command. And with a pair_style
defined that only computes 1-2 interactions. Then the "total" force will
be the component you want.