Regensburg 2007 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 20: Correlated Electrons - Poster Session
TT 20.64: Poster
Mittwoch, 28. März 2007, 14:00–17:45, Poster A
Sum rules and vertex corrections for electron-phonon interaction — •Oliver Rösch1,2, Giorgio Sangiovanni1, and Olle Gunnarsson1 — 1Max-Planck-Institut für Festkörperforschung, Stuttgart — 2Institut für Theoretische Physik, Universität zu Köln
We derive sum rules for the phonon self-energy and the electron-phonon contribution to the electron self-energy of the Holstein-Hubbard model in the limit of large Coulomb interaction U. Their relevance for finite U is investigated using exact diagonalization and dynamical mean-field theory. Based on these sum rules, we study the importance of vertex corrections to the electron-phonon interaction in a diagrammatic approach. We show that they are crucial for a sum rule for the electron self-energy in the undoped system while a sum rule related to the phonon self-energy of doped systems is satisfied even if vertex corrections are neglected. [1]
[1] O. Rösch et al., Phys. Rev. B (accepted); cond-mat/0607612.