Figure shows results of calculations where the COM distance between the monomers has been fixed, but the energy minimized with respect to other degrees of freedom at each step in the scan. This causes the dimer geometry to switch from the head-to-head configuration at short distance, to the head-to-tail configuration at longer distance. This behaviour has also been modelled and analyzed previously, using a 12-site polarizable model based on mobile charge densities described as harmonic oscillators. While the point charge model does not seem to reproduce this transition accurately, the new SCME potential description is almost identical to the QM results, using only 1+3 interaction sites. See section S6.1 in the Supporting Information, for a comparison of cluster interaction energies between the 12-site model and our work.