Fluctuation–dissipation approach to van der Waals potentials between atoms and dielectric bodies

Abstract

We consider the problem of an atom in its ground state located at some distance z from an infinite plane surface bordering a dielectric body. For this system the atom–dielectric interaction potential has been calculated by Mavroyannis in terms of the frequency-dependent dielectric constant ϵ(ω ) of the body. We rederive Mavroyannis’ result by defining a correlation function involving the virtual atomic dipole of the external atom and its image inside the dielectric and then evaluating it by means of the fluctuation–dissipation theorem. This approach does not depend on coupling with the vacuum field, it only takes into account cohesion forces, i.e. atomic interactions inside the solid since these are the only effects that determine both the dissipative and the absorptive part of ϵ(ω ).

Keywords:

• Van der Waals potentials
• Atoms
• Dielectrics
• Surface physics
• Atomic spectroscopy