Computer simulations of water and aqueous electrolyte solutions at interfaces
The results of computer simulations of water and aqueous electrolyte solutions in contact with smooth and corrugated walls are reviewed. Oxygen atom density profiles have been calculated by various authors from simulations using different water models in contact with hard walls, Lennard-Jones walls of various powers, and polarizable walls where the polarizability is described by image charges. These results for smooth walls are compared with the density profiles obtained for the vicinity of a corrugated platinum crystal. There is general agreement that the dipole vectors of the water molecules near the walls are preferentially oriented parallel to the interface. Dipole distribution functions are discussed with respect to the electrostatic surface potential drop. The inhomogeneities and anisotropics of water-water pair correlation functions near smooth and corrugated walls are presented in detail. The hydration shells of ions at interfaces differ from those in the bulk solutions as demonstrated by a simulation of a 2.2 molal LiI solution between Lennard-Jones walls. Finally, the self-diffusion coefficients, the hindered translational motions of the water molecules parallel and perpendicular to smooth and corrugated walls, and the librational motions are discussed, calculated from the simulations with the help of the corresponding velocity autocorrelation functions.