Thermodynamically Consistent Force Field for Coarse-Grained Modeling of Aqueous Electrolyte Solution.

We propose a thermodynamically consistent methodology to parameterize interactions between charged particles inside the dissipative particle dynamics (DPD) formalism. We used osmotic pressure experimental data as a function of the salinity in order to optimize interaction parameters. Results for NaCl aqueous solution show that both mean osmotic and activity coefficient of individual ions allow to determine the Na+-water, Cl--water and Na+-Cl- DPD repulsion parameters. A simple linear relationship between the hydration free energies of ions and the ion-water repulsion parameters that allows the parameterization of the complete series of halide and alkaline ions is proposed. Two strategies have been used to obtain anion-cation interaction parameters for halide and alkaline but NaCl. In the first one, parameters are obtained based on the numerical optimization of the anion-cation repulsion parameter with respect to experimental osmotic pressure data (with mean average deviations < 4%). Second, we propose a predictive approach based on the free energy difference of hydration energies of anions and cations in the spirit of the law of matching water affinities (LMWA) (with mean absolute relative deviation of about 13 %, and better than 6% if small ions (Li+ and F-) are removed).