Freitag vormittags Vorträge - Bunsentagung - Technische Universität ...

Freitag 21.05.2004, 14:50 Uhr
Vortrag - Theoretische Chemie
C
21
DFT Investigation of Binary Nanostructures
Sibylle Gemming 1 ,2 , Michael Schreiber 2 , Gotthard Seifert 1
1 Institut für Physikalische Chemie und Elektrochemie,
Technische Universität, D-01062 Dresden
2 Institut für Physik, Technische Universität, D-09107
Chemnitz
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