EVALUATION OF A MODEL POTENTIAL FUNCTION FOR Ar GRAPHITE INTERACTION USING COMPUTER SIMULATION

The transition from a liquid-like to a solid-like state for Ar on graphite at 77 K, although well characterized experimentally, is difficult to reproduce in simulation. We review briefly the possible second order contributions to and influence on an a priori potential function, which may account for this difficulty. These include: anisotropy effects, three body terms and induced interactions. In view of the overall complexity of such a potential function, we propose a 2-parameter model in which the surface barrier height and adsorbate intermolecular interactions can be vaned. It is found that a unique combination of parameters can bring simulation and experiment into much closer agreement than achieved hitherto.