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TT: Tiefe Temperaturen

TT 16: Posters Correlated Electrons, Measuring Devices, Cryotechnique

TT 16.11: Poster

Saturday, March 5, 2005, 11:00–16:30, Poster TU C

The Holstein-Hubbard Model away from Half-Filling — •Winfried Koller, Alex C. Hewson, and Dietrich Meyer — Department of Mathematics, Imperial College London

Recent experimental results in strongly correlated materials, such as fullerides, manganites and the high Tc compounds, have stimulated a renewed theoretical interest in the effects of electron-phonon interaction. The simplest model to examine the interplay of the electron-phonon and electron-electron interactions is Holstein-Hubbard model. This model has been predominantly studied under the assumption of particle-hole symmetry. Here we present results for the model away from half-filling using the dynamical mean-field theory in combination with the numerical renormalisation group. We calculate one-electron spectral densities and two-particle response functions. In particular, we examine the crossover from bipolaronic to polaronic behaviour, and compare our results with those derived from the many-body coherent-potential approximation (CPA).