The dispersion interaction energy for a pair of chiral molecules in their ground states is calculated using the multipolar form of quantum electrodynamics. The calculations go beyond the electric-dipole approximation, and the interaction Hamiltonian includes the electric-quadrupole, magnetic-dipole, and diamagnetic coupling terms. The energy is calculated using two methods: one with standard fourth-order perturbation theory and another with a response formalism. In the perturbation approach, the intermolecular coupling arises from two-photon exchange whereas in the response method, the energy shift is calculated from the response of one molecule to the Maxwell fields of the other. In both calculations retardation effects are taken into account. It is shown that the dispersion energy contains a contribution that depends on the relative handedness of the two molecules. An expression for this discriminatory energy shift, valid for all intermolecular separations beyond the electron overlap, is presented. In addition to the discriminatory energy shift, results are presented for the interaction energy shift between a molecule with electric-dipole polarizability and another with magnetic-dipole or electric-quadrupole polarizability. The limiting behavior of these shifts in the near and the far zone is examined.

• Received 29 June 1994

DOI:https://doi.org/10.1103/PhysRevA.50.4767