Systems investigated here include the benzene dimer, the [18]annulene dimer that we will call simply (annulene) 2 , porphyrin dimer, and a COF-1 dimer that we will call (COF1) 2 . Monomer units for these four systems are shown in Fig. . We will also consider (COF1) 2 with a mesitylene molecule between the monomer units, as this has been suggested to change the structure from offset-stacking to eclipsed-cofacial stacking. The COF-1 monomer unit was optimized at the TPSS+D3/def2-SV(P) level of theory, as the TPSS+D3 functional reproduces the 3.4 Å face-to-face separation of the parallel-displaced benzene dimer that is determined in high-accuracy calculations. The eclipsedcofacial (COF1) 2 structure was then optimized, subject to a constraint that both monomers remain planar, resulting in a face-to-face separation of R = 3.28 Å that is used for subsequent two-dimensional potential energy scans using XSAPT+MBD. For (COF1) 2 (mesitylene), the same procedures results in an interlayer separation R = 3.4 Å that is used for the two-dimensional scans in that system. For (porphyrin) 2 and (annulene) 2 we use separations of R = 3.7 Å (TPSS+D3/def2-TZVP level) and R = 3.2 Å (TPSS+D3/def2-TZVPD level), respectively. All calculations were performed using Q-Chem (v. 5.4), and all structures are available in the Supporting Information.