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CPP: Chemische Physik und Polymerphysik

CPP 6: Poster: Neue Methoden

CPP 6.4: Poster

Montag, 11. März 2002, 13:30–15:00, B

Molecular dynamics simulation of aqueous sodium chloride solution at the NaCl(001) interface with a polarizable water model — •Enno Oyen and Reinhard Hentschke — Physics Department and Institute for Materials Science, Wuppertal University, Gauss-Strasse 20, 42097 Wuppertal, Germany

The sodium chloride solution-NaCl crystal interface serves as an example of aqueous electrolytes at uncharged ionic surfaces. The surfaces of alkali halide particles in their saturated solutions play important roles in technologically relevant processes like corrosion, tertiary oil recovery, crystallization and flotation. Here the NaCl solution-salt crystal interface is investigated by classical molecular dynamics simulations at ambient pressure and generally at 298 K. A fluctuating charges version of the extended simple point charge (SPC/E) water model, the SPC/E-P model, is used to calculate structural and dynamical properties of the ions at the interface and in the bulk solution: density profiles and potentials of mean force including concentration dependencies, hydration numbers, and mobilities of ions parallel and perpendicular to the interface. We find that sodium ions are adsorbed selectively at the metastable NaCl(001) interface and their mobility is strongly reduced due to adsorption. Analogous calculations using the non-polarizable SPC/E model do not exhibit such an intense exothermic sodium ion adsorption, i.e. solvent polarization can significantly affect ionic distributions close to polar, but uncharged interfaces. In the case of SPC/E-P water, dipole moment profiles are calculated also.