The interaction of rare gas atoms with graphite surfaces. II. Adatom–adatom potentials

Abstract

The Gordon–Kim local density method is applied to the calculation of the interaction energy of pairs of neon, argon, and krypton atoms adsorbed on the basal plane of graphite. At the adatom–surface equilibrium separation, the adatom–adatom interaction potentials are found to be from 12% to 20% more repulsive than the gas phase counterparts. At much smaller adatom–surface separations, the adatom–adatom effective potential well depth is only 3% of the gas phase well depth. It is found that the nonadditive contributions to the interaction energy are more important for the smaller rare gas adatoms than for the larger ones. This trend is observed experimentally. It is concluded that rare gas films on graphite are too mobile to be in registry with the substrate.