Interactions between arrays of point charges (multipoles) associated with potential energies that depend on distance. Multipole interactions are an important feature of intermolecular forces. An n-pole is a set of n charges having an n-pole moment but not a lower moment. A monopole is a single charge and the monopole moment is the charge. A dipole consists of two opposite charges and thus has no overall charge (and hence no monopole moment). Higher multipoles are the quadrupole and the octupole. The interaction potential energy between multipoles falls off with distance increasingly rapidly as the order of the multipoles increases. If a 2^m-pole interacts with a 2ⁿ-pole, the interaction potential energy, V, varies with distance r as V = c/(r^m+n−1), where c is a constant. The rapid fall-off with distance, as the order increases, is due to the set of charges appearing to tend towards neutrality (as seen from outside). The multipole interactions with the largest interactions are: ion-ion, ion-dipole, dipole-dipole, and dispersion interactions.