Berlin 2008 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 18: Correlated Electrons: Low-dimensional Systems - Materials 2

TT 18.2: Talk

Tuesday, February 26, 2008, 15:30–15:45, H 2053

Realistic Parameters for the description of the two-dimensional molecular metal Θ-BEDT-TTF — •Andreas Dolfen¹, Erik Koch¹, Laura Cano-Cortes², and Jaime Merino² — ¹Institut für Festkörperforschung, Forschungszentrum Jülich, Germany — ²Departamento de Física Teórica de la Materia Condensada,

In order to study correlations in the two dimensional molecular metal Θ-(BEDT-TTF)₂I₃ we employ density-functional theory to calculate realistic parameters for extended Hubbard models.

We evaluate the hopping matrix elements for different angles and distances of two molecules observing a surprising sensitivity with respect to certain molecular orientations. This is because a large part of the molecular orbital is situated next to the sulphur atoms outside the molecules.

The Coulomb parameters, however, are less sensitive. We calculate the on-site as well as the longer range Coulomb repulsion including intra-molecular screening and screening due to all the other molecules (BEDT-TTF and I₃).