Conformations are named according to their rotation and stacking pattern, with additions for short axis rotations in BzQuin and for relative oxygen direction in DBTO. Conformation names start with the numerical value of their rotation angle, followed by one or two letters indicating lateral displacement patterns. Most conformers are simply labeled SR, for "slipped and rotated." X denotes a conformer where the centre points (either centre of mass or centroid of central ring) of the two monomers remain superimposed, while the confomers are rotated relative to each other around this common axis. For dimers whose monomers have only sixmembered rings (Anth, Phen, BzQuin, and Py), the possibility of graphitic-type stacking arises, where rings of one monomer are centred over 3-way ring junctions of the other. This motif is designated G. For BzQuin, if a conformer has a short axis inclination near 180 • , then an F (for "flipped") is appended to the conformer name. For DBTO, one of three letters, I, O, or P, is appended to describe the relative orientation of the oxygen atoms. If each oxygen atom is oriented toward the molecular plane of the opposing monomer, then an I (for "inward") is appended to the conformer name. If each oxygen atom is oriented away from the molecular plane of the opposing monomer, then an O (for "outward") is appended to the conformer name. If one is oriented toward the opposing monomer's molecular plane, but the other is oriented away, then a P (for "parallel") is appended. Finally, if two or more distinct conformers are not otherwise distinguished by our naming system, we then append a number to the end of the name, with conformers with lower Gibbs free energies having lower numbers.