Regensburg 2000 – wissenschaftliches Programm

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O: Oberflächenphysik

O 11: Postersession (Eröffnung)

O 11.48: Poster

Montag, 27. März 2000, 19:00–22:00, Bereich C

Alkali-Intercalation in Transition-metal Dichalcogenides — •C. Ramírez, O. Tiedje, and W. Schattke — Institut für Theoretische Physik und Astrophysik Christian-Albrechts-Universtit"at zu Kiel

In the past, extensive experimental and theoretical investigations of layered transition-metal dichalcogenides have been done. These compounds change their physical properties rather dramatically upon intercalation with alkali atoms. Charge transfer from the intercalant to the host lattice accompanies the reaction. The alkali metals are very interesting as intercalants since they have a strong tendency to loose their single valence electron, which limits the hybridization between the alkali metal and the host valence bands. Ab initio calculations for the intercalation complex LiTiSe₂ have been carried out within local density approximation employing supercells, normconserving pseudopotentials in separable form, and a plane-wave basis. The relaxation of the alkali atom from the surface through the three layer TiSe₂ sandwich into the van der Waals gap has been investigated to explore energetically favorable paths of intercalation. The dimensionality and the dispersion of the valence bands are studied to detect intercalation-induced changes, and to check the validity of the rigid-band model.