[lammps-users] Question concerning pair style

I am studying two regions. I want atoms in the first region to interact only with the atoms from the first region and atoms from the second region to interact only with atoms from the second region, the sw potential is used. I tried something like this but got an error. Any help would be appreciated.

pair_style sw
pair_coeff * * si.sw Si NULL NULL NULL

pair_coeff * * si.sw NULL Si NULL NULL

You need to do this with atom types or groups, not regions. And use
the neigh_modify exclude command to turn off neighbor interactions
between the two sets of atoms.