how to apply purely repulsive potential?

Dear all
how can i describe repulsive potential between two atom with specific formula (k(R − r)3, r < R,) for scratch and indentation simulation ?
is there special command for this kind of potential?
Regards and thanks in advance.

You can either use pair_style table to specify the forces and energies for any R within the cutoff in a file, or use pair_style python (slower) where you can provide a Python function that returns what you need.