Elastic interaction of two atoms adsorbed on a solid surface

The long-range interaction of two adsorbed atoms mediated by the elastic distortion of the substrate is calculated classically for an elastically isotropic substrate. For identical atoms, the interaction is repulsive; for different atoms, it can be repulsive or attractive. It varies as ρ^?3 with the distance ρ between the two adsorbed atoms. This is the same spatial dependence as for the dipole - dipole interaction between two adsorbed atoms. For two xenon atoms adsorbed on gold, the elastic interaction is somewhat smaller than the dipole-dipole interaction. The interaction energy is inversely proportional to the shear modulus of the substrate, so that it may become quite large near a distortive phase transition.