The calculation of intermolecular potentials

Abstract

The use of intermolecular perturbation theory to rationalize intermolecular forces and to provide a framework for concepts of intermolecular interactions has been routine for many years. It has long been assumed, however, that the route to accurate calculations of intermolecular potentials lies through ab initio supermolecule calculations, and it is only in relatively recent times that this view has been challenged. It is now clear that accurate intermolecular potentials can be constructed for regions where the molecules do not overlap by assembling the components described by long-range intermolecular perturbation theory —the electrostatic, induction and dispersion terms— though perturbation theory itself does not necessarily provide the best way to calculate them. At short range, the repulsion must be added, and the long-range terms modified to account for the effects of overlap. Here too, perturbation theory provides a useful to accurate numbers.