Multipole expansion of the retarded interatomic dispersion energy. III. The long and short range behaviour

The long-range asymptotic expression for the multipole expansion of the retarded interatomic dispersion energy is shown to consist of contributions from electric dipole-dipole, dipole-quadrupole and quadrupole-quadrupole interactions, all varying as the inverse seventh power of the interatomic separation. The general expressions for these interactions lead to short-range series expansions which extend results obtained earlier with the help of the Breit hamiltonian.