Dresden 2009 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 24: Correlated Electrons: (General) Theory 2
TT 24.2: Vortrag
Mittwoch, 25. März 2009, 09:45–10:00, HSZ 301
The Dynamical Vertex Approximation: spatial correlations beyond Dynamical Mean Field Theory — •Alessandro Toschi1, Andrey Katanin2, 3, and Karsten Held1 — 1Institut für Festkörperphysik, Technische Universität Wien, Austria — 2Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany — 3Institute of Metal Physics, Ekaterinburg, Russia
Progress in going beyond the purely local description of the Dynamical Mean Field Theory (DMFT) has been recently obtained through cluster extensions of the method, which include spatial correlations within the cluster size. Long-range spatial correlations may be, however, of vital importance: They are responsible for a rich variety of phenomena, ranging from magnons and screening of the Coulomb interaction to quantum criticality. Our new diagrammatic approach, coined “Dynamical Vertex Approximation” (DΓA)[1,2], provides for a systematic treatment of the effects of long-range spatial correlations beyond DMFT. Specifically, we use the DΓA with a Moriyaesque λ correction for studying the impact of antiferromagnetic fluctuations on the spectral function in the whole phase diagram of the Hubbard model in three[1] and intwo dimensions[2,3] . The diagrammatic nature of DΓA, moreover, makes the algorithm well suited for a generalization to the more realistic case of multi-band Hamiltonians.
[1] A. Toschi, A. Katanin, and K. Held, Phys. Rev. B, 75, 045118 (2007).
[2] K.Held, A. Katanin, and A. Toschi, Prog. Theo. Phys. Suppl, 176, in print (arXiv: 0807.1860).
[3] A. Katanin, A. Toschi, and K. Held, arXiv:0808.0689 submitted to Phys. Rev. B