Here, ε inter i j and σ inter i j are the 12-6 Lennard-Jones (LJ) parameters and q i and q j the Coulomb point charges (see Section S2 of the Supporting Information for further details). The first term on the right side of equation ( ) is null for an isolated molecule and the whole potential energy energy of the system in the gas phase coincides with the QMD intra-molecular term: