A good starting point for any binary system potential would be the single element potentials and maybe a combination of both for the mixed potential.
A sample format 4 potential file for a binary system (EAM potential) is available
here (with the
#G header line).
Starting potentials for analytic potentials can be generated with the makeapot script.
There are several examples available for the different interactions:
Coulomb potential for binary system: Download
Dipole potential for binary system: Download