Superscripts (mn) indicate mth-order perturbation theory with respect to the intermolecular Coulomb operator and nth-order in the Møller-Plesset fluctuation potentials for the monomers. The fact that n = 0 in Eq. ( ) means that this approach is based on uncorrelated (Hartree-Fock) wave functions for the monomers. The exchange-dispersion term E