At first glance, these (COF1) 2 surfaces are quite dif-ferent from the ones considered above but in fact they share many of the same features. Most important is that a slip-stacked conformation is preferred, with three local minima that are evident in Fig. and perhaps more evident in Fig. . The deepest of these (E int = -115.5 kcal/mol) occurs at displacements ∆x = 1.25 Å and ∆y = 0.75 Å, and in Fig. , one can observe a lowenergy region corresponding to slip-stacking by ≈ 1.25 Å in any direction. This is the magnitude of the lateral offset that our calculations predict, relative to the eclipsedcofacial or AA-stacking geometry, and it is similar to offsets of 1.4-2.8 Å that have been computed for this and other COFs, depending somewhat on the material and on the computational method. Lateral offsets of this magnitude are much smaller than what one would expect for AB-stacking, in which the vertices of one COF layer are centered within the voids of the adjacent layer. In comparison to the 14.8 Å pore size of the COF-1 monomer, such small displacements are not much different from eclipsed-cofacial stacking.