The Van der Waals interaction between an atom and a solid

Abstract

Measurements of the scattering of neutral atoms by metal cylinders have indicated a serious discrepancy between theory and experiment for the strength of the long-range Van der Waals interaction. To clarify the content of the theory, we present here a formal analysis of the Van der Waals interaction between an atom and a solid, based on the approach of McLachlan. A key quantity in the theory is the response of the solid to an external, time-dependent dipole. This response is amenable to classical analysis, and we calculate it for a variety of model systems. When the solid may be treated as a continuum with a flat surface, the concept of surface impedance allows a convenient parameterization and we may incorporate thereby magnetic effects, non-local dielectric response, and the influence of finite layers in the solid. We also study the modifications induced by a rough surface, finding the average change in the coupling strength in the presence of weak roughness.