Regensburg 2002 – wissenschaftliches Programm

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O: Oberflächenphysik

O 2: Hauptvortrag

O 2.1: Hauptvortrag

Montag, 11. März 2002, 10:15–11:00, H36

Density functional studies of the initial oxide formation on metal surfaces — •Georg Kresse — Institut fuer Materialphysik, Univ. Wien, Sensengasse 8/12, A-1090 Wien, AUSTRIA

A combination of theoretical and experimental methods is used to study the initial steps of the formation of vanadium oxides and palladium oxides on Pd(111). For the case of vanadium oxides, several different phases with different stoichiometries are found to be stable at varying experimental conditions (pressure and temperature). Density functional theory and simple thermodynamic arguments reveal an astonishingly complex phase diagram in very good agreement with experiment. For Pd-O on Pd(111), an incommensurate LEED pattern is observed experimentally at high oxygen pressures. Ab initio calculations, experimental core level spectra, scanning tunneling microscopy and diffraction experiments allow to identify the structure unambiguously. Among other things, the talk will also emphasize that density functional calculations are now sufficiently fast and stable to obtain the ionic groundstate structures by means of simulated annealing calculations. The Pd-O/Pd(111) structure, for instance, was solved by extended molecular dynamics lasting several 10000 steps.