title: MP2 study on adsorption of hydrated Na+ and Au+ cations on the Au(111) surface.
abstract: The interactions of Na+ and Au+ cations with an Au(111) surface in the presence and absence of water molecules were investigated using Au18 and Au22 cluster models and the MP2 method with a triple-zeta valence basis set. The interactions between Na+ ions and the Au(111) surface were found to be primarily electrostatic, contrary to the much stronger Au+-Au(111) interactions that were dominated by orbital contributions. The largest CP-corrected MP2 adsorption energies were -156.9 kJ/mol for Na+ and -478.7 kJ/mol for Au+. When hydrated, Na+ prefers to be completely surrounded by water molecules rather than adsorbed to the surface, whereas Au+ remains adsorbed to the surface as water molecules bond with each other and with the Au surface. CP correction did not change the relative adsorption energy trends of Na+ or Au+ ions, but it had an effect on the interaction energy trends of the hydrated cations because of the weak water-surface and water-water interactions.
authors.affiliation: Department of Chemistry, University of Joensuu, P.O. Box 111, FI-80101 Joensuu, Finland.
authors.forename: Antti J
authors.initials: AJ
authors.lastname: Karttunen
authors.forename: Tapani A
authors.initials: TA
authors.lastname: Pakkanen