T A B L E 1 Spin-opposite and spin-component scaled double hybrid density functional approximations tested in this work, incl. their opposite-(c OS T ) and same-spin (c SS T ) scaling parameters to be used for the ground-state SCS/SOS-MP2 treatment, based on the indirect SCS/SOS-CIS(D) components established in ref. approximate coupled cluster singles doubles (SCS-CC2 ) level with the def2-TZVP atomic-orbital (AO) basis set. The binding of each excimer was studied by excited-state interaction energies as a function of the distance between the two monomers, with intramolecular coordinates frozen in their excimer geometry. Interaction energies along this curve are defined as the total excited-state energy relative to the the total excited-state energy at 16 Å, a distance that approximates a non-interacting dimer. These can be thought of as analogous to ground-state interaction energy curves, where negative interaction energies indicate binding in this excited state. The minimum of each curve defines the binding of the excimer structure characterised by the dissociation energy, D e , and equilibrium distance, r e , in Cartesian coordinates (r e , -D e ).