These dimer geometries are generated by keeping the COM of one of the monomer at the origin, and the another monomer COM at a distance R, with points evenly distributed over a hemisphere. The distance between the COMs of the monomers is varied from 3.0 Å to 7.0 Å with a 0.25 Å separation. The dispersion energy of the CH 3 CN dimers is calculated using existing dispersion coe cients C ref n , previously optimized to reproduce ab initio dispersion energy for CH 3 CN 43 (see Table in the Supporting Information). We use the same Berthelot combination rule, equation 20, as in reference for the linear MeCN. In this way, the C i n coe cients are least-squares fitted to reproduce the ab initio asymptotics of the dispersion. See Figure in the Supporting Information for the comparison of the fitted and reference dispersion energy.