Long-Range (Retarded) Intermolecular Forces

Abstract

The Casimir and Polder retarded dipole—dipole energy of interaction between two ground-state (non-degenerate) atoms is expressed in terms of sine and cosine integrals. This result should be accurate for all interatomic separations R. In the range of moderately large separations (discussed in the preceding paper), where the charge distributions do not overlap and where R is small compared to λ/0=(αΔε)−1, the Casimir and Polder results can be expanded in the form Eint=R−6C6+α2R−4W4+α3R−3A+α4R−2B+···.This expansion is only accurate for R/λ/05.0.