Lower bound to the- Long-range interaction energy of two identical rare gas atoms in the restricted Hartree-Fock approximation

The localized orbital description for a homonuclear diatomic molecule leads to a lower bound for the interaction energy of two identical rare gas atoms, computed in the restricted Hartree-Fock (RHF) approximation. At all sufficiently large internuclear separations, the lower bound is positive, implying that the interaction energy must approach zero from above. Therefore the RHF approximation cannot predict any asymptotic attractive interaction for systems consisting of two like rare gas atoms.