Berlin 2008 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 23: Correlated Electrons: (General) Theory
TT 23.3: Vortrag
Mittwoch, 27. Februar 2008, 14:30–14:45, H 0104
Dual Fermion Approach to Susceptibility of Correlated Lattice Fermions — •Sergey Brener1, Hartmut Hafermann1, Alexey N. Rubtsov2, Mikhail I. Katsnelson3, and Alexander I. Lichtenstein1 — 1I. Institute of Theoretical Physics, University of Hamburg, 20355 Hamburg, Germany — 2Department of Physics, Moscow State University, 119992 Moscow, Russia — 3Institute of Molecules and Materials, Radboud University, 6525 ED Nijmegen, The Netherlands
We show how the two-particle Green function can be obtained within the framework of the recently developed Dual Fermion approach. This facilitates the calculation of the susceptibility in strongly correlated systems where long-ranged non-local correlations cannot be neglected. We formulate the Bethe-Salpeter equations for the full vertex in the particle-particle and particle-hole channels and introduce an approximation for practical calculations. The scheme is applied to the two-dimensional Hubbard model at half filling. The spin-spin susceptibility is found to strongly increase for the wavevector q=(π,π), indicating the antiferromagnetic instability. Combining this approach with the cluster dual formalism and applying it to the Hubbard model at finite doping we get the possibility to capture all the essential physics of HTSC.