Hannover 2013 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 56: Poster III

Q 56.25: Poster

Donnerstag, 21. März 2013, 16:00–18:30, Empore Lichthof

Non-equilibrium Self-energy-functional theory and conserving approximations — •Felix Hofmann and Michael Potthoff — I. Institut für Theoretische Physik -- Universität Hamburg, Hamburg, Deutschland

The self-energy-functional theory [1] provides a general framework for the systematic construction of non-perturbative, thermodynamically consistent approximations in order to study strongly correlated systems in the thermodynamical limit in and out of equilibrium and proves to respect certain conservation laws [2]. On the space of self-energies a functional can be constructed which is stationary at the physical self-energy and equals the physical grand canonical potential when evaluated at the latter. Without approximating the (formally unknown) functional, the variational principle can be evaluated by restricting the self-energies to a subspace of (numerically) solvable reference systems. This is done self consistently, such that the results are obtained in the thermodynamical limit. By choosing appropriate classes of reference systems, theories like variational-cluster-approach (VCA) and dynamical-mean-field-theory (DMFT) can be derived from SFT as well as improved variants. Likewise, SFT allows for studying phases and phase transitions (by numerical means) as for example the Mott metal-insulator transition, magnetic phase transitions or the transition from antiferromagnetic to the superconducting phase in Hubbard-like and spin models.

[1] M. Potthoff, AIP Conf. Proc. 1419, pp. 199-258 (2011)

[2] F. Hofmann and M. Potthoff, to be published