Dresden 2003 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 2: Systeme korrelierter Elektronen I
TT 2.7: Vortrag
Montag, 24. März 2003, 11:30–11:45, HSZ304
Electron-phonon vertex in the two-dimensional one-band Hubbard model — •Zhongbing Huang1, Werner Hanke1, Enrico Arrigoni1, and Douglas J. Scalapino2 — 1Institut für Theoretische Physik, Universität Würzburg, am Hubland, 97074 Würzburg, Germany — 2Department of Physics, University of California, Santa Barbara, California 93106
Two independent QMC techniques, i.e., frozen phonon and response calculations, are used to study the effects of electronic correlations on the electron-phonon vertex function in the two-dimensional one-band Hubbard model. Our simulations are performed for both ionic- and covalent-type electron-phonon interactions. In agreement with previous (1/N) and slave-boson calculations, we find that in strong electron-electron coupling, the backward scattering with large phonon momentum is suppressed much more than the forward scattering with small phonon momentum. However, for the covalent electron-phonon coupling, we arrive at a new and unexpected result, with the enhancement or suppression depending crucially on the electron momentum. This implies a strong electron-phonon coupling in the underdoped regime for physically relevant scattering processes. In the weak-coupling regime, our numerical simulations are in good agreement with standard diagram expansions.