Structure and dynamics of water and hydrated ions near platinum and, mercury surfaces as studied by MD simulations

Results of various MD simulations of pure water and those with either an additional lithium or iodide ion near a Pt(100), a rigid and a liquid mercury surface are reported. The potentials describing the interactions with the metal surfaces are based on ab initio calculations of a water molecule or an ion and metal clusters of different sizes. The flexible BJH and the rigid TIP4P models for water are employed and the ion-water interactions are also derived from ab initio calculations. The structure at the interfaces for pure water at the three different surfaces is described by oxygen, hydrogen and mercury atom density profiles. The effect of all three metal surfaces on the structure of the hydration shells of the lithium and the iodide ion are discussed in detail and the free energies are reported as a function of distance from the rigid mercury surface. The spectral densities of the hindered translational motions of both ions parallel and perpendicular to the Pt(100) and the liquid mercury surface are presented. Copyright (C) 1996 Elsevier Science Ltd