In the benzene dimer, E elst becomes increasingly attractive at smaller values of R, as depicted in Fig. , whereas many textbooks would argue that short-range electrostatics should be repulsive due to interpenetration of the electron clouds on the two monomers. To debunk this myth, we consider an even simpler system: Ar 2 . Energy components for Ar 2 are plotted as a function of R in Fig. ). Note that E elst (R) < 0 at all values of R, indicating a strictly attractive electrostatic interaction, even for values of R that are much smaller than the equilibrium separation.