To make this explicit, Fig. juxtaposes two-dimensional contour plots of exact and quadrupolar electrostatics for (C 6 H 6 ) 2 . 200 One of the coordinates in these plots is the intermolecular distance R, representing the face-to-face separation for parallel arrangements of the dimer and face-to-center distance for perpendicular orientations. The other coordinate is a lateral displacement that generates slip-stacking in the cofacial arrangement, and in perpendicular orientations moves the dimer between T-shaped and L-shaped geometries.