A final peculiarity of the PBE+D3 calculations reported in Ref. 18 is the authors' decision to include the correlation energy within the dispersion energy. While it is true that the D3 correction alone is not a pure dispersion energy, because it is an empirical correction that is contaminated by other contributions (in the vdW contact region where the monomer charge densities overlap), certainly not all correlation effects are dispersion. This definition has the curious effect that dispersion alone favors offset-stacking in the analysis of Ref. 18, by about 5 kcal/mol. Physically speaking, E disp usually favors geometries that maximize the number of atoms in close spatial proximity, due to its steep falloff with distance, therefore dispersion often competes directly with Pauli repulsion. In porous systems such as COF-1, the dispersion energy should therefore be most attractive in the eclipsed-cofacial geometry because any sizable offset places the atoms of one layer atop voids in the adjacent layer(s). Indeed, we observe this behavior using the MBD model for E disp , where it is used with our preferred LRC-ωPBE description of the monomers (Fig. ) or in conjunction with PBE (Fig. ). Even the D3 model is most attractive in the eclipsed-cofacial configuration (Fig. ). As such, the conclusion in Ref. 18 that dispersion alone favors offset-stacking appears to result from a misattribution of correlation effects.