Systematic trends in van der Waals interactions: Atom–atom and atom–surface cases

Abstract
Correlations are discussed for van der Waals interactions [V(x)] of two types: between two atoms and between an atom and a surface. Letting ε be the well depth and Cn be the asymptotic dispersion coefficient [such that V(x) ∼ - Cnx-n], it is shown that (C n/ε)1/n is proportional to the equilibrium distance and to the decay length of the repulsive part of the interaction. A simple model which describes and unifies these correlations is presente