This analysis suggests that offset-stacking is driven by a competition between short-range forces, Pauli repulsion and dispersion, rather than longer-range electrostatics as claimed in some other ab initio calculations. 179 This is true both at R = 3.4 Å, where charge penetration makes the electrostatic interaction attractive, but also at R = 3.8 Å where the quadrupolar picture holds and E elst > 0. Charge-transfer effects, which would appear in E ind , 157 must also be negligible, consistent with previous analyses. At smaller face-to-face distances such as R = 3.4 Å, the electrostatic term is not only attractive but also (weakly) favors the cofacial sandwich geometry, precisely opposite to the Hunter-Sanders prediction! Only the vdW potential is able to rationalize offsetstacking at both R = 3.4 Å and R = 3.8 Å. The same conclusion is reached using alternative forms of energy decomposition analysis based on DFT calculations. 3.2. Substituent Modifications. Absent an electrostatic basis for stacking, the synthetic chemist may be limited in how precisely an offset can be controlled, with consequences for optoelectronic properties. As such, it is important to consider whether the vdW picture continues to provide a rationale for offset-stacking in the presence of substituents. Polar substituents may enhance |E elst | beyond the paltry values seen in benzene dimer, although we also consider non-polar substituents as well. Despite profound differences in the dipole-quadrupole interactions between the substituent and the opposite aromatic ring, qualitative features of both potential energy profiles are captured by E vdW . This includes a double-minimum that is characteristic of offset-stacking, which is not observed in the corresponding profile of E elst . Because the dipole-quadrupole interactions are attractive at short range in these examples, the double-well minimum in E int does appear at smaller values of R as compared to the double well in E vdW , as the (attractive) electrostatic interactions have been turned off in E vdW . Slip-stacking behavior remains in the absence of electrostatics, however, because it is driven by dispersion and Pauli repulsion.