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TT: Fachverband Tiefe Temperaturen

TT 35: Postersession Transport: Nanoelectronics, Quantum Coherence and Quantum Information, Fluctuations and Noise

TT 35.14: Poster

Mittwoch, 25. März 2009, 14:00–18:00, P1A

Density functional theory on a lattice: Transport through a small interacting region — Michael Dzierzawa, Ulrich Eckern, •Stefan Schenk, and Peter Schwab — Universität Augsburg

Density functional theory is the method of choice for calculations of the electronic structure of complex materials. In recent years the method has been applied to study charge transport through systems of molecular size. However it is clearly necessary to determine the limits of the approach to assess the obtained results. To this end we suggest to study simple lattice systems, where the comparison with exact calculations is possible.

Hence we investigate a one-dimensional system with spinless fermions consisting of a small interacting region between two noninteracting leads. In particular we study the linear conductance through the interacting region. We find that for this specific system a naive calculation of the conductance, i. e. by ignoring the exchange-correlation kernel, is often sufficient. The local density approximation performs rather badly even for weak interaction, whereas the so-called exact-exchange approximation gives sensible results. We also propose an exact diagonalization procedure to obtain a non-local exchange-correlation potential for strongly interacting systems.