Regensburg 2007 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 20: Correlated Electrons - Poster Session

TT 20.77: Poster

Mittwoch, 28. März 2007, 14:00–17:45, Poster A

The one-dimensional Hubbard model: A benchmark for variational cluster approximations — •Matthias Balzer, Michael Potthoff, and Werner Hanke — Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Am Hubland D-97074 Würzburg

Important physical properties of lattice models of strongly correlated electrons are often dominated by short-range spatial correlations. Starting from the purely local (atomic) physics, short-range correlations can be included step by step within cluster approximations generated by the self-energy-functional theory. The one-dimensional Hubbard model is considered to benchmark various cluster schemes: the plain cluster perturbation theory (CPT), the variational cluster approach (VCA) using different sets of variational parameters as well as extensions of the VCA including bath degrees of freedom. Calculations are performed at zero temperature for clusters up to 10 sites. The results for the filling dependence of the chemical potential and the transition to the Mott insulator are compared to the exact Bethe ansatz. Several questions concerning thermodynamical consistency, cluster boundary conditions, optimal choice of variational parameters, spectral functions etc. are investigated. The applications of variational cluster methods for the study of the filling-controlled Mott transition in two dimensions are discussed.