Abstract
A self consistent field configuration interaction (SCF-CI) surface for H2H2 was calculated for the specific purpose of comparing various anisotropic model pair potentials for the repulsive interaction around the Van der Waals minimum. Different functional forms and methods of treating the anisotropy were tested, and a new approach to the treatment of the anisotropy developed. It is shown that for simple exponential potentials such an approach to the anisotropy rivals the site-site form for accuracy, combines more elegantly with accurate representations of the long range potential, and shows greater promise for the development of more complex potentials for many molecules.