Regensburg 2004 – scientific programme

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TT: Tiefe Temperaturen

TT 32: Theoretische Modelierung von Materialien mit korrelierten Elektronen

TT 32.8: Talk

Friday, March 12, 2004, 12:00–12:15, H18

Zero Temperature Quantum Monte Carlo for Dynamical Mean Field Theory — •Martin Feldbacher¹, Karsten Held¹ und Fakher Assaad² — ¹Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, D-70569 Stuttgart — ²Universität Würzburg, Institut für Theoretische Physik I, Am Hubland, 97074 Würzburg

In recent years there has been a revival of interest in Kondo-like physics, in particular in quantum dot systems and in connection with the dynamical mean field theory (DMFT). The numerical solution of the underlying Anderson impurity models is, however, limited: In the Numerical Renormalization Group treatment the effort grows exponentially with the number of orbitals, allowing not more than two interacting orbitals; the Hirsch-Fye Quantum Monte Carlo (QMC) algorithm on the other hand scales like T⁻³ (T: temperature) and quickly becomes too expensive in CPU time. This limitation is especially severe when DMFT is used to model materials with strong electron correlations where, in order to observe the physics of interest, low temperatures need to be achieved.

We propose a projective QMC algorithm for the Anderson impurity model which converges rapidly to the ground state. With this new impurity solver we study the Mott-Hubbard metal-insulator transition in the Hubbard model, demonstrating that it gives reliable “T=0” DMFT results.