In order to further interpret the origin of such improvement, in Figure we study the correlation between the ML/MM coupling energy computed by ME (and ME+P) using Mulliken charges computed in in vacuo, with a ME coupling energy computed with a set of Mulliken charges calculated in presence of classical water molecules ({q vac M ull } and {q sol M ull }, respectively, in Figure ). For the sake of consistency, we will notate this ME coupling energy also as E ME ML/MM , despite the prediction of such set of charges by ML-methods seems to be more challenging than the prediction of in vacuo charges. It can be seen that the coupling energy computed with charges obtained from polarized electron densities ({q sol M ull } in Figure ) perfectly match the obtained by the polarizable mechanical embedding in which in vacuo atomic charges ({q vac M ull } in Figure ) are employed along with a polarization correction. In other words, this illustrates that the polarization term accounts for the polarization induced by the MM system in the atomic charges (or the electron densities from which they are derived). This results highlights the equivalence between a ME+P approach in which in vacuo derived atomic charges are corrected with atomic polarizabilities, and a ME approach in which atomic charges derived in the presence of the environment (namely, the solvent) are employed.