water molecules and with an electrolyte unit C n A m in addition to 150 -(n + m) water molecules by performing MD simulations in the NVT ensemble for 20 millions steps to gather statistics after equilibration during 1 millions steps. By taking the difference between the variation of Helmholtz free energy and variation of internal energy, we obtain an estimation of the variation of entropy ∆S CnAm for electrolyte solvation at infinite dilution. The results for the variation of internal energy and of entropy are displayed respectively in the middle and left columns of Table . Again, the values for ∆U CnAm and ∆S CnAm are all negative and are more negative for smaller ions, except for CsCl that displays a more negative entropy than that their hydration number differs greatly. This is because divalent cations present strong polarization and charge transfer effects that can not be modeled with simple empirical force fields. Better force fields has been developed to model properly divalent cations in solution.