Both of these dimers afford nearly identical energy profiles as compared to benzene dimer at similar separation (cf. Fig. ), with essentially identical stacking energies and similar offsets. As in the benzene dimer, E vdW largely parallels E int meaning that short-range forces, rather than longer-range dipolar forces, drive the preference for offset-stacking. Despite the pyridine monomer's dipole moment (µ = 2.2 D), the electrostatic energy is similar in (pyridine) 2 and in (benzene) 2 , being maximally repulsive in the cofacial arrangement and peaked at E elst ≈ 0.5 kcal/mol, when the face-to-face separation is comparable.