ELLIPSOID CONTACT POTENTIAL - THEORY AND RELATION TO OVERLAP POTENTIALS

We propose and analyze the properties of a simple, computationally eff icient pair potential for nonpolar molecules based on the contact func tion for ellipsoidal cores. We discuss the relation of this potential to the Gaussian overlap potential and show that the present potential gives the correct extension of the ideas of the Gaussian overlap poten tial to mixtures. We show that this potential obeys a form of the prin ciple of corresponding states and derive an expression for the second virial coefficient. As this potential has an incorrect symmetry at lar ge separations, we derive another contact potential that behaves isotr opically at infinite separation. Unfortunately, this potential does no t have the good computational features of the one investigated here.