Regensburg 2002 – wissenschaftliches Programm
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SYQT: Quantentransport auf molekularen Skalen
SYQT 3: Quantentransport auf molekularen Skalen
SYQT 3.3: Hauptvortrag
Montag, 11. März 2002, 17:00–17:30, H2
Electron transport in nanosystems — •Frank Großmann, Rafael Gutiérrez, and Rüdiger Schmidt — Institute for Theoretical Physics, Dresden University of Technology, D-01062 Dresden
In this contribution, we point out to the significance of ab-initio conductance calculations in order to identify appropriate objects for a future molecular electronics. To this end, we are combining the Landauer formalism with density functional theory and molecular dynamics and apply it to metals, as well as to pure carbon systems and to organic molecules.
For atomic metal chains and clusters a pronounced odd/even oscillation of the conductance as a function of the number of atoms is observed. Furthermore, for the clusters, a strong dependence on the orientation of the objects between the leads, as well as on the isomeric state is predicted [1]. In pure carbon systems with a fullerene as the central unit, new electro-mechanical switching functions can be realized. By the rotation of the fullerene in between the leads, e. g., the conductance changes by several orders of magnitude. Moreover, molecular dynamical calculations show that the conductance qualitatively changes after structural relaxation and therefore, realistic theoretical predictions are only to be expected for relaxed systems. For the HBC (C42H18) molecule at a gold surface, the I(V)-characteristics at room temperature is determined by the (broadened) electronic levels of the single molecule. Our theoretical predictions agree very well with recent experimental results.
This work is supported by the DFG through FOR 335.
[1] R. Gutiérrez, F. Großmann, O. Knospe, and R. Schmidt, Phys. Rev. A 64, 013202 (2001).