Solvation structure, hydrogen bonding, and ion pairing in dilute supercritical aqueous NaCl mixtures

We review molecular dynamics simulations of infinitely dilute supercritical aqueous NaCl solutions to determine the solvation structure and the solute-induced effect on water-water hydrogen bonding and report new simulation results on the extent of the ion pairing. Our simulation studies indicate that Na+ and Cl- ions as a pair or as isolated infinitely dilute ions form strong solvation structures in SCW, even though the water-water hydrogen bonding is not affected. Within the context of the models we are using, there is strong indication of a high degree of Na+/Cl- ion pairing.