Halide and sodium ion parameters for modeling aqueous solutions in TIP5P-Ew water

We present new Lennard-Jones parameters for the halide ions Cl−, Br− and I− and for the alkali ion Na+, to be used in combination with the TIP5P-Ew water model. Molecular dynamics simulations and thermodynamics integration are used to obtain one set of parameters to reproduce the experimental hydration free energy, the ion–oxygen coordination number and the structure of the solvation layer. The reported parameters reproduce the experimental hydration free energies within the numerical uncertainty of the simulations and their prediction of structural quantities are in good agreement with experimental results. The diffusion coefficients are calculated as a further test: the obtained parameters provide a reasonable prediction of experimental diffusion coefficients.