Van der Waals interaction between an atom and a solid surface

This paper contributes to the theory of the long-range attractive polarization force between a neutral atom and a crystalline solid surface in the nonrelativistic limit. The first two terms in the asymptotic expansion of the polarization energy are used to define an atom-solid potential of the form $V_{\mathrm{pol}}=-C{(Z-Z_0)}^{-3\mathrm{}}$. The constant $C$ appearing in this expression is known from the earlier work of E. M. Lifshitz. The present paper gives a theory of the position of the "reference plane," $Z_0$, which is important in applications to physisorption. An explicit expression for $Z_0$ is first derived for atoms interacting with a jellium metal and with an insulating crystal consisting of atoms which interact via dipole-dipole forces. These model calculations are then incorporated into a computation of the polarization energies of rare-gas atoms physisorbed on noble-metal surfaces. The computed energies are found to be consistent with observed adsorption energies.