Regensburg 2010 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 11: CE: Low-dimensional Systems - Materials 2

TT 11.3: Talk

Tuesday, March 23, 2010, 10:00–10:15, H18

LDA+Slave-boson mean-field theory: a powerful low-energy tool for realistic strongly correlated systems — •Christoph Piefke and Frank Lechermann — I. Institut fuer Theoretische Physik, Universitaet Hamburg, Jungiusstrasse 9, 20355 Hamburg

The rotationally invariant slave-boson mean-field theory (RISB) has proven to be a powerful tool to investigate large parameter spaces of arbitrary strongly interacting systems [1,2]. In this approach, complex fermionic interactions are described by means of an electon-operator decoupling into a quasiparticle part and localized bosonic degrees of freedom. A set of constraints ensures that this mapping does not leave the Hilbert space of the original problem. At saddle-point, a self-consistent mean-field solution is obtained.

As an efficent method for demanding problems, RISB is used to investigate LDA-based models for realistic materials with strong electronic correlations. Resulting physical quantities like the quasiparticle weight or the local spin correlations for, e.g., the Na_xCoO₂ system [3], are in very good agreement with more accurate many-body approaches. Moreover the additionally extracted multiplet weights for atoms and clusters in the strongly correlated regime provide further important insight into the competition between itinerancy and localization.

[1] T. Li, P. Wölfle, and P. J. Hirschfeld, Phys. Rev. B 40, 6817 (1989).

[2] F. Lechermann, A. Georges, G. Kotliar and O. Parcollet, Phys. Rev. B 76, 155102 (2007).

[3] F. Lechermann, Phys. Rev. Lett. 102, 046403 (2009).