The interaction energy per monomer of the clusters calculated using the optimized geometry is shown in Figure (see also Table in the Supporting Information). As seen from Next, we test the SCME potential performance on the ↵-phase of solid acetonitrile, for which no information is included in the parametrization. The experimental unit-cell geometry of ↵-phase ACN 57 is relaxed using periodic QM calculations. See section S7 in the Supporting Information for computational details. The QM-calculated lattice constant is slightly underestimated compared to experiment; all within 2.4-4.4% (see Table in the Supporting Information). Table shows the comparison of cohesive properties (equilibrium volume, cohesive energy, and bulk modulus) to QM calculations, and Figure visually compares the QM and SCME geometries. All calculations have been performed without inclusion of temperature. The SCME model is able to predict the equilibrium volume, V 0 , of ACN within 1.7% deviation from the QM results, whereas the point charge model has a larger error of about 12%. The deviations from the bulk modulus (B 0 ) of ACN obtained from the point charge and SCME models are about 9.4% and 7.8% respectively. Furthermore, the point charge-computed cohesive energy (E coh ) deviation with respect to the QM result is about 15%. The deviation is almost halved when using the SCME potential.