Effects of ion concentration and solvent composition on the properties of water-methanol solutions of NaCl. NPT molecular dynamics computer simulation results

Abstract: Isothermal-isobaric molecular dynamics simulations are used to examine the microscopic structure and other properties of a model solution consisting of NaCl salt dissolved in water-methanol mixture. The SPC/E water model and the united atom model for methanol are combined with the force field for ions by Dang [J. Amer. Chem. Soc., 1995, 117, 6954] to describe the entire system. Our principal focus is to study the effects of two variables, namely, the solvent composition and ion concentrations on the solution's density, on the structural properties, self-diffusion coefficients of the species and the dielectric constant. Moreover, we performed a detailed analysis of the first coordination numbers of the species. Trends of the behaviour of the average number of hydrogen bonds between solvent molecules are evaluated.