For interpretative purposes we might approximate one or both of the electrostatic potentials using a multipole expansion. For example, 48) where Q A , µ A , and Θ A are the total charge, the dipole moment vector, and the quadrupole moment tensor of molecule A, respectively. One could make a multipole expansion for the density ρB (R) and then recast Eq. ( ) into a form involving multipole-multipole interactions. In so doing, it is important to remember that Eq. ( ) is in an asymptotic expansion that is valid only for a test charge that is located at a distance R that is large compared to the details of the molecular charge distribution, ρA (r). In fact, the multipole expansion is divergent as R → 0. Perhaps more convincingly, it is readily demonstrable that nonbonded close-contact distances (including typical equilibrium geometries of vdW complexes) are not usually in the asymptotic regime where the electrostatic potential is well described (or even qualitatively described) by leading-order multipoles. An example is shown in Fig. for three different structures of the benzene dimer.