Van der Waals forces between an atom and a surface

Abstract

The theory of electrical images is used to derive Van der Waals forces at the surface of a solid, which is treated as a continuous dielectric medium. The theory gives the attraction between a single atom and the surface, between two atoms which are both close to the surface and between two bodies separated by a gap. The forces come out in terms of the dielectric constant of the solid and the electric polarizability of the atom at imaginary frequencies. The method of images breaks down at distances greater than about 500 å, and an exact treatment of the electromagnetic field fluctuations near the surface leads to the same force as Lifshitz's general theory.