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TT: Fachverband Tiefe Temperaturen

TT 23: Correlated Electrons: (General) Theory

TT 23.13: Vortrag

Mittwoch, 27. Februar 2008, 17:30–17:45, H 0104

Gutzwiller approach to phonon renormalization in the correlated SSH Model — •Ernst von Oelsen — Institut für Physik, BTU Cottbus, PBox 101344, 03013 Cottbus, Germany

The SSH Model [1] is supplemented with a Hubbard repulsion term in order to study the influence of electronic correlations on transitive phonon excitations. Our investigations are based on the time-dependent Gutzwiller approximation [2] and we restrict to the undimerized case. Eliminating double occupancy fluctuations via an anti-adiabaticity condition we obtain the quadratic fluctuations in the phonon and electronic density fields. Already on this level we find correlation-induced softening for small wave vectors which eventually induces an instability in addition to the Peierls nesting mechanism. In addition we show that inclusion of a Hubbard repulsion creates additional couplings between electrons and phonons beyond the bare transitive interaction. Finally we calculate the phonon self-energy which is compared with the uncorrelated case.

[1] W. P. Su and J. R. Schrieffer and A. J. Heeger, Phys. Rev. B 22, 2099 (1980)

[2] G. Seibold and J. Lorenzana, Phys. Rev. Lett. 86, 2605 (2001)