Derivation of atomic forces, monomer geometry of the acetonitrile molecule, multipole moments and polarizabilities of the acetonitrile, traceless conditions of the moments and polarizabilities, dispersion coe cients of ACN, additional dimer geometries of ACN used in optimizing the parameters, schematic representation of ACN clusters, comparison to 12-Site polarizable force field, computational details of the solid simulations, computational details of the liquid simulations, damping functions.