Dresden 2014 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 84: Correlated Electrons: (General) Theory

TT 84.5: Vortrag

Donnerstag, 3. April 2014, 10:30–10:45, HSZ 304

One-particle irreducible functional approach: A route to diagrammatic extensions of the dynamical mean-field theory — •Georg Rohringer¹, Alessandro Toschi¹, Hartmut Hafermann², Karsten Held¹, Vladimir Anisimov^3,4, and Andrey Katanin^3,4 — ¹Institute for Solid State Physics, Vienna University of Technology, 1040 Vienna, Austria — ²Centre de Physique Théorique, École Polytechnique, CNRS, 91128 Palaiseau Cedex, France — ³Institute of Metal Physics, 620990, Ekaterinburg, Russia — ⁴Ural Federal University, 620002, Ekaterinburg, Russia

We present an approach[1] which is based on the one-particle irreducible (1PI) generating functional formalism and includes electronic correlations on all length-scales beyond the local correlations of dynamical mean field theory (DMFT). This formalism allows us to unify aspects of the dynamical vertex approximation (DΓA) and the dual fermion (DF) scheme, yielding a consistent formulation of nonlocal correlations at the one- and two-particle level beyond DMFT within the functional integral formalism. In particular, the considered approach includes one-particle reducible contributions from the three- and more-particle vertices in the dual fermion approach, as well as some diagrams not included in the ladder version of DΓA. To demonstrate the applicability and physical content of the 1PI approach, we compare the diagrammatics of 1PI, DF and DΓA, as well as the numerical results of these approaches for the half-filled Hubbard model in two dimensions.
G. Rohringer, A. Toschi, K. Held, V. I. Anisimov, and A. A. Katanin, Phys. Rev. B 88, 115112 (2013)