Regensburg 2013 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 58: Poster Session III (Solid-liquid interfaces; Scanning probe and other methods; Electronic structure theory; Spin-orbit interaction)

O 58.15: Poster

Mittwoch, 13. März 2013, 18:15–21:45, Poster B1

Reduced Ceria Surfaces: Ab initio computation of the electronic structure with the GGA+U method — •Alexander Hampel, Daniel Grieger, and Frank Lechermann — 1. Institut für Theoretische Physik, Universität Hamburg, Germany

This work deals with the investigation of the atomic and electronic structure of oxygen reduced ceria (111) surfaces within the GGA+U formalism as implemented in the Vienna ab initio Simulation Package (VASP). Within the GGA+U formalism one can take account of the strongly correlated f-states. The ab initio investigation starts with the determination of the correct lattice constant and the choice of the Hubbard-U value in the bulk to reproduce a correct insulating band gap. Using periodic supercells the electronic structure of the surface is calculated and the main properties of the clean surface are pointed out. This leads to the investigation of the oxygen vacancies. The change of the ceria structure by the lack of an oxygen atom on the surface and in the sub-surface are investigated. Surface energies give a good estimation of the probability for the (111) surface to appear and formation energies estimate the stability of the defects. Finally, we have a look on the change of electronic structure initiated by the vacancies, mainly the density of states. So one can see the advantages of the GGA+U treatment of the f-states and where the strongly correlated electrons are located.