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TT: Fachverband Tiefe Temperaturen

TT 47: Poster Session Correlated Electrons 2

TT 47.25: Poster

Mittwoch, 18. März 2020, 15:00–19:00, P2/3OG

The Chebyshev expansion as solver for the variational cluster approximation at finite temperature — •Jan Lotze and Maria Daghofer — University of Stuttgart, Functional Matter and Quantum Technologies, Pfaffenwaldring 57, 70569 Stuttgart

The variational cluster approximation (VCA) based on self-energy functional theory (SFT) [1] can be used to study correlated-electron Hamiltonians: Instead of the original systems self-energy, that of a ’reference system’ is considered. While full diagonalisation suffices for small reference systems, larger systems require the Lanczos method or a quantum Monte Carlo method to be tractable. An alternative approach is to expand the reference systems Green’s function in Chebyshev polynomials [2].

Here, thermodynamic and dynamical properties of the one- and two-dimensional Hubbard model at finite temperature are presented to illustrate the Chebyshev expansion in comparison to the Lanczos method as solver of the reference system.

[1] M. Potthoff, ’Self-Energy-Functional Theory’, in Strongly Correlated Systems - Theoretical Methods (Springer, 2012)

[2] A. Braun and Schmitteckert, Phys. Rev. B 90, 165112 (2014)