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TT: Fachverband Tiefe Temperaturen

TT 15: Correlated Electrons: Metal-Insulator Transition 2

TT 15.3: Vortrag

Dienstag, 24. März 2009, 10:00–10:15, HSZ 301

Realistic model Hamiltonians for correlated organics — •Erik Koch — Institut für Festkörperforschung und Institute for Advanced Simulation, Forschungszentrum Jülich, 52425 Jülich

For a description of strongly correlated materials we have to resort to model Hamiltonians. These generalized Hubbard models have to be simple enough that they can be treated by non-perturbative many-body approaches, yet complex enough to capture the specifics of real materials. We discuss how to derive such realistic model Hamiltonians for molecular crystals starting ab-initio. We focus in particular on the calculation of screened Coulomb matrix elements for which we use a two-step approach: treating intra-molecular screening with density-functional theory, while describing inter-molecular screening via a lattice of distributed polarizabilities. We discuss the surprising screening effects that appear in highly polarizable lattices and present model Hamiltonians for quasi one- and two-dimensional organics.