Studies on the retarded interaction between neutral atoms - I. Three-body London-van der Waals interaction of neutral atoms

An expression for the non-additive, three-body interaction energy of three neutral atoms is deduced, by the methods of quantum electrodynamics. Non-relativistic reduction and dipole approximation result in an expression which for interatomic separations R small compared to the wavelengths of typical atomic transitions reduces to the triple-dipole energy varying as R–9 (Axilrod & Teller), whereas at distances large compared with these wavelengths, the three-body interaction energy becomes proportional to R–10, owing to the influence of retardation.