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One of the main open problems in the field of transport in strongly interacting nanostructures is the understanding of currents beyond the linear response regime. In this work, we consider
the single-impurity Anderson model and use the adaptive time-dependent density matrix renormalization group (tDMRG) method to compute real-time currents out of equilibrium [1]. We first focus on the particle-hole symmetric point where Kondo correlations are the strongest and then extend the study of the nonequilibrium
transport to the mixed-valence regime. We first demonstrate that the steady state is independent of the initial conditions. As a main result, we present accurate data for the current-voltage
characteristics of this model, and present a comparison with other methods that are currently
being applied to this problem [2]. As tDMRG is typically implemented with a real-space representation of the noninteracting leads, the Kondo regime, due to the emergent exponentially large Kondo screening length, is difficult to access. We therefore apply tDMRG to Wilson leads [3], i.e., noninteracting leads with a logarithmic
discretization as used in the numerical renormalization group, and show that in the limit of small biases, perfect conductance can be obtained from tDMRG at the particle-hole symmetric point at much smaller Kondo temperatures than using a real-space representation of the leads. Time permitting, we shall discuss the application of tDMRG to more complex nanostructures as well.
[1] F. Heidrich-Meisner, A.E. Feiguin, E. Dagotto. Phys. Rev. B 79, 235336 (2009). [2] J. Eckel J. Eckel, F. Heidrich-Meisner, S.G. Jakobs, M. Thorwart, M. Pletyukhov, R. Egger, arXiv:1001.3773. [3] L.G.G.V. Dias da Silva, F. Heidrich-Meisner, A.E. Feiguin, C.A. Busser, G.B. Martins, E.V. Anda, and E. Dagotto, Phys. Rev. B 78, 195317 (2008) |
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