Berlin 2008 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 22: Transport: Poster Session

TT 22.38: Poster

Mittwoch, 27. Februar 2008, 14:00–18:00, Poster B

Quantum conductance from the irreducible polarization function — •Swantje Heers, Arno Schindlmayr, Daniel Wortmann, and Stefan Blügel — Institut für Festkörperforschung, Forschungszentrum Jülich, 52425 Jülich, Germany

The standard approach to quantum transport, which involves a combination of ab initio density-functional theory and the Landauer formula, successfully describes the conductance of nanojunctions at a qualitative level, but it remains unclear how the Coulomb interaction can best be incorporated into this single-particle picture of ballistic transport. An alternative approach proposed by P. Bokes et al. [Phys. Rev. B 69, 245420 (2004); 76, 125433 (2007)] that uses a relation between the polarization function and the conductance formally includes such noncoherent effects. In order to demonstrate its applicability in numerical calculations for a semi-infinite scattering setup with proper boundary conditions we investigate transport through model metal-vacuum-metal interfaces with a piecewise constant potential varying in one dimension only. Starting from the non-interactiong Green function we calculate the polarization function and then the conductance. The necessary extrapolation to zero frequency and the dependence on relevant convergence parameters are demonstrated. In the first instance we neglect the electron-electron interaction and find that the conductance in the single-particle picture coincides with the Landauer formula. This scheme is hence a promising avenue to take exchange and correlation effects into account in future transport calculations.