molecule investigated here has a permanent dipole moment. However, at least one molecule in each non atom•••atom complex has a permanent quadrupole moment. Thus, the induced dipole moment asymptotically decays for those systems like R -4 , the electric field from a quadrupole, which originates from the first-order interaction in the operator V . Hence, the theory introduced here should be asymptotically correct and accurate for such a class of systems, provided that the monomer density is reproduced correctly.