Regensburg 2013 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 39: Focused Session: Frontiers of Electronic Structure Theory 4 (jointly with HL and O)

TT 39.3: Talk

Wednesday, March 13, 2013, 11:15–11:30, H36

Effective onsite interactions for materials with strong non-local Coulomb interactions — •Malte Schüler¹, Alexander Lichtenstein², Mikhail I. Katsnelson³, and Tim Wehling¹ — ¹Institut für Theoretische Physik, Universität Bremen, D-28359 Bremen, Germany — ²1. Institut für Theoretische Physik I, Universität Hamburg, D-20355 Hamburg, Germany — ³Radboud University Nijmegen, NL-6525 AJ Nijmegen, The Netherlands

sp-Electron systems and low-dimensional materials often comprise strong local Coulomb interaction and non-local Coulomb interaction at the same time. Here we report on a method to map a generalized Hubbard model with non-local Coulomb interaction to an effective Hubbard model with strictly local Coulomb terms U^*. With the examples of graphene and silicene we show that the non-local Coulomb interaction can reduce the effective local interaction up to a factor of 2. The U^* model is defined by a variational principle with respect to the free energy. In this framework, obtaining the effective interaction requires non-local charge correlation functions for various parameters of the effective Hubbard model, which are calculated by the determinant quantum Monte Carlo method. The temperature dependence of the effective interaction is discussed.