Berlin 2012 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 45: Correlated Electrons: Poster Session

TT 45.37: Poster

Thursday, March 29, 2012, 15:00–19:00, Poster B

With DFT and Ewald-summation to realistic parameters in molecular crystals — •Michael M. E. Baumgärtel, Andreas Dolfen, and Erik Koch — German Research School for Simulation Sciences, Forschungszentrum Jülich and RWTH Aachen University, 52425 Jülich, Germany

For the study of strongly correlated molecular crystals the determination of realistic model parameters is an open problem. Rather than fitting to experimental data or semi-empirical approaches, we demonstrate how to determine material-specific parameters for an extended Hubbard model ab-initio. The model can be restricted to HOMO and LUMO by renormalization of the screened Hubbard parameters. While intra-molecular screening is treated within density functional theory, we describe inter-molecular screening by a lattice of distributed polarizabilities. However, the long-range dipole-dipole interaction makes this approach computationally difficult. We can, though, obtain rapidly converging dipole-response matrix elements in reciprocal space using Ewald-summation. We demonstrate this method for TTF-TCNQ.