In the case of AC(2)-QM/MM calculations, the cutoff distance for the addition of two-body contributions was varied from 6 a.u. in steps of 1 a.u. until energy convergence of 1.5 kJ•mol -1 was achieved for a single-point calculation. This procedure was carried out for each individual system. The resulting cutoff value was then used for all subsequent AC(2)-QM/MM calculations of the respective crystal.