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TT: Tiefe Temperaturen
TT 32: Theoretische Modelierung von Materialien mit korrelierten Elektronen
TT 32.1: Talk
Friday, March 12, 2004, 10:15–10:30, H18
Quasiparticles from quantum Monte Carlo: Effective mass and Wilson ratio for K3C60 — •Erik Koch and Olle Gunnarsson — Max-Planck-Institut für Festkörperforschung, Stuttgart
Taking advantage of the fixed-node approximation to stabilize excited states, we calculate quasiparticle energies by quantum Monte Carlo. We apply this approach to a model describing K3C60 and show that it works surprisingly well. We determine how the quasiparticle dispersion changes with increasing correlation and compare to the many-body enhancement of the Pauli susceptibility. While the self-energies for our model seem to depend only weakly on the momentum (and band-index), we find a Wilson ration that appears to behave qualitatively different from what is expected from dynamical mean-field theory.