Berlin 2012 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 45: Correlated Electrons: Poster Session
TT 45.10: Poster
Donnerstag, 29. März 2012, 15:00–19:00, Poster B
Continuous unitary transformation of the single impurity Anderson model — •Jörn Krones and Götz S. Uhrig — TU Dortmund, Theoretische Physik I, 44221 Dortmund, Germany
Quantum impurity systems, such as the considered single impurity Anderson model (SIAM) have been of significant interest throughout the last decades. An efficient way to deal with the exponentially varying energy scales
in such models is the numerical renormalization group (NRG). The free orbital regime (FO) at high energies crosses over to the local moment regime (LM) as energies are decreased with a final crossover to the strong coupling
regime (SC) at very small energies. The two crossovers are determined by characteristic energies. The crossover from FO to LM is determined by the coulomb interaction U while the crossover from LM to SC is determined
by the exponentially small Kondo temperature Tk. Perturbation theory provides a good description for energies E≳ Tk but breaks down for E≈ Tk.
It is our aim to use non-perturbative continuous unitary transformations as a new approach to investigate the full energy regime from the conduction electron bandwidth D down to exponentially small energies
E≪ Tk. We want to construct an effective Hamiltonian in form of a linear chain similar to Wilson’s treatment, labeled by single particle energies and interaction terms.