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DS: Fachverband Dünne Schichten

DS 41: Layer Properties: Electrical, Optical, and Mechanical Properties II

DS 41.6: Vortrag

Donnerstag, 23. März 2017, 16:15–16:30, CHE 91

The Phase Diagram of the hexagonal Hubbard Model with Dyson-Schwinger Equations — •Katja Kleeberg and Lorenz von Smekal — Institut für Theoretische Physik, Justus-Liebig Universität Gießen

We study the semimetal-insulator transition on the hexagonal lattice within the framework of Dyson-Schwinger equations. The coupled Dyson-Schwinger equations are formulated for the two competing phases, either realized by a charge-density wave formation or a spin-density wave formation. We investigate the critical behaviour for zero temperature within an extended Hubbard model with on-site and nearest-neighbour interaction. The critical coupling strengths are determined for an unscreened interaction (i.e. in Hartree-Fock approximation) and with static Lindhard screening included. The resulting phase diagrams for the fermionic Hubbard model are compared. The Dyson-Schwinger euqations are solved numerically by fixed-point iteration on GPU's for very large lattices which gives access to the study of the associated magnetic and finite-size scaling behaviour.