Dispersion contributions to surface energy

The concept of dispersion self-energy of a molecule or atom of finite size in an inhomogeneous dielectric medium is developed. The self-energy, which is always finite and its dependence on distance from an interface dividing two media, is evaluated. The surface energy of the interface is obtained in terms of the self-energies of all the molecules of the medium. The resulting expression is shown to reduce in suitable approximation to forms similar to those derived by Fowkes and by Craig.