[lammps-users] How can I realize it in Lammps

My simulation will involve two groups atoms. One of them (1) would be kept rigid, while the other group (2) is of interest.

In addtion, I would like following situation:

when groups 2 approach to the rigid group atoms 1, there would be a high repulsion force.

I am wondering whether there is some command in Lammps can realize such function.

Many thanks.

Fix setforce will hold some atoms stationary (if there velocity is also 0),
or just don't time integrate them. Lots of pair styles have strong
repulsion at short separation of atoms.