Lateral variation of the physisorption potential for noble gases on graphite

The adsorption potential of noble gases on graphite is calculated. The method used is the summation of two-body anisotropic interactions between the adatom and each carbon atom, which takes into account the graphite anisotrophy. The lateral variation which results depends on the uncertain role of anisotrophy in the repulsive part of the interaction. In any case, the computed variation is of the order of twice the value computed by Steele [Surf. Sci. 36, 317 (1973)] and is widely used. Our conclusion is consistent with thermodynamic data.