Structural and dynamical properties of concentrated aqueous NaOH solutions: a computer simulation study

Molecular dynamics simulations of NaOH aqueous solutions have been performed with a flexible model of the water molecule. Ion-ion interactions have been described by the (12-6) Lennard-Jones type and coulomb potentials. The concentration of the solutions ranged from 0.5 to 19 M. The structures of hydration shells of the ions were analysed using the radial distribution functions, Voronoi tessellations, the running and O'Keeffe coordination numbers and other tools. Structural properties obtained from simulations agreed reasonably well with results of the available experimental data. The dynamical properties were calculated and compared with experimental measurements. A particularly careful analysis was applied to the topological properties of the ionic structures in solution. The results of calculations suggest an existence of the ordered structures of ions in solution and supports the Ruff theory of ionic quasi-lattices in concentrated solutions.