Regensburg 2013 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 41: Focussed Session: Frontiers of Electronic Structure Theory IV (jointly with HL and TT)
O 41.3: Vortrag
Mittwoch, 13. März 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.