Many-Body Aspects of Physical Adsorption

A theory is presented for determining the effect of many-body interactions on the dispersion energy of a pair of gas molecules adsorbed on a crystalline solid. The formalism is based on a reaction field technique and includes potential nonadditivity to fourth order. Model calculations are carried out for the change in the interaction energy between a pair of Ne atoms, a pair of Ar atoms, and a pair of Kr atoms adsorbed on solid Xe by summing over the Xe lattice. The results are analyzed and compared with calculations based on a model which treats the solid as a continuous dielectric.