Accessing thermodynamics from dynamical cluster-embedding approaches

Gang Li, Werner Hanke, Alexei N. Rubtsov, Sebastian Bäse, and Michael Potthoff
Phys. Rev. B 80, 195118 – Published 30 November 2009

Abstract

Dynamical quantum-cluster approaches, such as different cluster extensions of the dynamical mean-field theory (cluster DMFT) or the variational cluster approximation (VCA), combined with efficient cluster solvers, such as the quantum Monte Carlo (QMC) method, provide controlled approximations of the single-particle Green’s function for lattice models of strongly correlated electrons. To access the thermodynamics, however, a thermodynamical potential is needed. We present an efficient numerical algorithm to compute the grand potential within cluster-embedding approaches that are based on novel continuous-time QMC schemes. It is shown that the numerically exact cluster grand potential can be obtained from a quantum Wang-Landau technique to reweight the coefficients in the expansion of the partition function. The lattice contributions to the grand potential are computed by a proper infinite summation over Matsubara frequencies. A proof of principle is given by applying the VCA to antiferromagnetic (short-range) order in the two-dimensional Hubbard model at finite temperatures.

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  • Received 7 August 2009

DOI:https://doi.org/10.1103/PhysRevB.80.195118

©2009 American Physical Society

Authors & Affiliations

Gang Li and Werner Hanke

  • Institute for Theoretical Physics and Astrophysics, University of Würzburg, Am Hubland, 97074 Wüzburg, Germany

Alexei N. Rubtsov

  • Department of Physics, Moscow State University, 119992 Moscow, Russia

Sebastian Bäse and Michael Potthoff

  • I. Institute for Theoretical Physics, University of Hamburg, Jungiusstr. 9, 20355 Hamburg, Germany

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Issue

Vol. 80, Iss. 19 — 15 November 2009

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