Use of a dissociative potential to simulate hydration of Na⁺ and Cl^- ions

We have developed interatomic interaction parameters for Na⁺ and Cl^- hydration using the dissociative water potential of Mahadevan and Garofalini [J. Phys. Chem. B 2007, 111, 8919] suitable for molecular dynamic simulations. Simulations were performed for small ion-water clusters Na(H ₂O)_n⁺ (n = 1-6) and Cl(H₂O) _m^- (m = 1-5), as well as dilute aqueous solutions of the ions in water, reproducing the structure and energies found in the literature. A simulation of an HC1 molecule in water demonstrated the dissociation of the molecule. The Na⁺ and Cl^- ion - ion interaction parameters also reproduce the energy and density of crystalline NaCl. A series of simulations of NaCl at progressively increasing temperatures from 300 to 1400 K produced solid densities varying by less than 1% from experiment.