Regensburg 2019 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 2: Correlated Electrons: Electronic Structure Calculations and Other Theoretical Topics

TT 2.8: Vortrag

Montag, 1. April 2019, 11:30–11:45, H7

Thermodynamics of the metal-insulator transition in the extended Hubbard model — •Malte Schüler^1,2, Erik van Loon^1,2, Mikhail Katsnelson³, and Tim Wehling^1,2 — ¹Institut for Theoretical Physics, Universtity of Bremen — ²Bremen Center for Computational Materials Science, Universtity of Bremen — ³Institute for Molecules and Materials, Radboud University, Nijmegen

Due to ineffective screening, low-dimensional materials often comprise strong local and non-local Coulomb interaction at the same time. In the corresponding extended Hubbard model, nonlocal interactions can raise the order of the metal-insulator transition and under certain circumstances lead to a discontinuous first-order transition. Here, we investigate the square lattice at half filling and find a first-order transition which is far from any charge-density instability. We discuss the thermodynamics of this transition and elucidate its experimental observability based on the corresponding jump on entropy. We use the Peierls-Feynman variational principle to approximate the extended Hubbard model by an effective Hubbard model. This requires the calculation of non-local charge correlation functions for various parameters of the effective Hubbard model, which we obtain by the determinant quantum Monte Carlo method.