Mat. Figs. and). As expected, the results are not consistent between setups with different box sizes and cutoffs. After applying the free-energy correction to ∆G raw , which accounts for both non-Coulombic and finite-size effects, the agreement between the FG, FG/S and CG+B schemes improves substantially. The maximum deviation between the CG+B and FG results is about 12 kJ mol -1 . However, these results differ from the solvation free energies calculated under NPT conditions with P = 1 bar, which lead to ∆G corr = -465.0 kJ/mol and -283.4 kJ/mol for Na + and Cl -, respectively. The reported NVT simulations exhibit a significant underpressure due to electrostriction. The scaling of the compressibility with s 3 might dampen this effect in the CG region by allowing the solvent molecules to get closer to the ions, which may explain why, for both ions, the solvation free energies calculated with the CG+B scheme are closer to the NPT results than those for the FG and FG/S schemes. The experimentally determined hydration free energies are -420.2 kJ mol -1 -307.8 kJ mol -1 for Na + and Cl -, respectively.