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M: Metallphysik

M 18: Postersitzung

M 18.17: Poster

Dienstag, 9. März 2004, 14:30–16:30, Saal C

DFT investigation of nanostructured binary compounds — •Michael Schreiber¹, Sibylle Gemming^1,2, and Gotthard Seifert² — ¹Institut für Physik, Technische Universität, D-09107 Chemnitz — ²Institut für Physikalische und Elektrochemie, Technische Universität, D-01062 Dresden.

Density-functional band-structure calculations were carried out for two-shell metallic nanowires from Au and from AgAu and PdAu alloys. All structures are local minima of the formation energy and more stable than the planar Au(111) surface. The stability of the most favourable structure increases in the order PdAu₈ < Au₉ < AgAu₈. This trend coincides with the tensile stress acting on the central monatomic chain. An analysis of the electronic structure shows that the binding between the two shells is not strongly directional. Yet, the interatomic interaction along the central chain is weakened compared to the interaction in the monatomic wire, thus the tensile stress along this direction is alleviated. In Au₉ and AgAu₈ the central conductance channel is depopulated, in PdAu₈ not. These findings rationalise the lower conductivity of PdAu nanocontacts compared with AgAu contacts obtained recently by break junction experiments. [1] www.abinit.org