Regensburg 2007 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 31: Low-dimensional Systems - Models I
TT 31.1: Talk
Thursday, March 29, 2007, 17:45–18:00, H19
Spectral broadening due to long-range Coulomb interactions in the molecular metal TTF-TCNQ — •Erik Koch1, Andreas Dolfen1, Laura Cano-Cortés2, Jaime Merino2, Jörg Behler3, Karsten Reuter3, and Bernard Delley4 — 1Institut für Festkörperforschung, Forschungszentrum Jülich — 2Universidad Autónona de Madrid — 3Fritz-Haber-Institut, Berlin — 4Paul-Scherrer-Institut, Villigen
We employ density-functional theory to calculate realistic parameters for an extended Hubbard model of the molecular metal TTF-TCNQ. Considering both intra- and intermolecular screening in the crystal, we find that longer-range Coulomb interactions along the molecular stacks, as well as inter-stack coupling are of importance. Contrary to past belief, these terms do not lead to the formation of a Wigner lattice, but simply broaden the spectral function. We show how this can be understood already in perturbation theory. Moreover we calculate the effect of the nearest neighbor repulsion on the Luttinger parameter.