Response function approach to van der waals’ interaction between atom and metal surface

Abstract

Van der Waals’ attractive interaction between a neutral atom and a metal surface (semi-infinite jellium) is studied via dielectric response approach in the non-retarded limit. It is shown that the interaction energy can be written in terms of the same form factorF(k, ω), which appears in the formula for dynamic image potential and which depends on the density-density response function of only the metal. The interaction energy written as the change in the zero-point energy of the electromagnetic fluctuations is expressed in terms of a secular determinant whose elements consist of the response function of the metal and the dynamic polarizability of the atom. The usual classical result is obtained when the coupling between the atom and metal is small. In the present analysis, it is shown that for short atom-metal separations, this coupling is important and yields substantial modification over the classical result. Numerical results for such situations are presented for the non-dispersive description of metal and a few inert gas atoms.