Dresden 2006 – wissenschaftliches Programm

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DF: Dielektrische Festkörper

DF 3: Poster Session

DF 3.7: Poster

Montag, 27. März 2006, 09:30–17:00, P1

DFT investigation of stepped titanate surfaces — •Walter Alsheimer, Sibylle Gemming, and Gotthard Seifert — Physikalische Chemie und Elektrochemie, TU Dresden, D-01062 Dresden.

The structural and electronic properties of vicinal (10n) surfaces of barium titanate were investigated by density-functional band-structure calculations. A plane-wave pseudopotential technique was employed for the (10n) surfaces with n < 5, and systems with larger terraces were studied with a density-functional-based tight-binding method. For the small system sizes, both methods yield considerable structure changes compared with the bulk geometry. These changes are mostly confined to the step edge and the two unit cells adjacent to it, thus from n=4 on the interaction between two adjacent step edges decreases. The density of electronic states exhibits only minor changes due to the deviations from the nominal stoichiometry at the step. The electric field far above the surface follows the nominal (10n) termination plane. Close to the step edge stronger local variations of the field occur, which may influence the adsorption geometry of polar or polarisable molecules.