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TT: Fachverband Tiefe Temperaturen

TT 32: Correlated Electrons: Poster Session

TT 32.40: Poster

Donnerstag, 28. Februar 2008, 14:00–18:00, Poster B

A new DCA scheme for calculating two-particle correlation functions of the 2D Hubbard model — •Stephan Hochkeppel, Fakher Assaad, and Werner Hanke — Institut für Theoretische Physik und Astrophysik, Universität Würzburg

Based on the Dynamical Cluster Approximation (DCA), we present a new approach to calculate two-particle Green’s functions for Hubbard-type models. In a first step, the DCA together with quantum Monte-Carlo as a cluster solver is used to compute the single-particle spectral functions (A(k,ω)) of the hole-doped Hubbard model. U(1) as well as SU(2) symmetry breaking is allowed so as to access superconducting states (dSC) as well as antiferromagnetic (AF) order. The temperature dependence of A(k,ω) from the paramagnetic to the dSC phase is studied in detail, the aim being a detailed study of the evolution of the pseudogap.

Two-particle quantities are computed within a quantum cluster approach, where the dynamical vertex is extracted from the cluster and the DCA dressed Green functions are used to calculate the bubble. The quality of the new approach is tested by comparing the resulting Neel temperature to that obtained by allowing for symmetry breaking within the DCA. Signatures of spin- and charge-correlation functions in the corresponding single-particle spectral functions are studied and resolved in detail.