Linear dependence of the interaction energy on intramolecular distance for adsorbed or clustered diatomic molecules

The dependence of several molecular properties (polarizabilities, multipole moments) of adsorbed diatomic molecules on the intramolecular distance are discussed within time-independent perturbation theory. The nearly linear dependence of the intermolecular interaction energy and molecular properties rationalizes the small variation of the property functions compared with those for the gas state. This relative independence of the property functions was demonstrated numerically in a previous paper using an iterative procedure for molecular hydrogen adsorbed in a zeolite-A-type framework.