Berlin 2018 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 72: Poster Session: Correlated Electrons

TT 72.84: Poster

Mittwoch, 14. März 2018, 15:00–19:00, Poster B

The finite-temperature Lanczos method as solver for the variational cluster approach — •Jan Lotze and Maria Daghofer — Universität Stuttgart, Institut für Funktionelle Materie und Quantentechnologien, 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 [2] to be tractable. Considering systems at finite temperature increases the numerical burden even further. Demanding on top of this the resolution of degenerate states in the reference system requires to switch from the regular Lanczos method to the Band Lanczos method.

Here, thermodynamic and dynamical properties of the one- and two-dimensional Hubbard model at finite temperature are presented to illustrate the finite-temperature Lanczos and Band Lanczos method as solver of the reference system. The effect of degeneracies onto the results is discussed.
M. Potthoff, ‘Self-Energy-Functional Theory’, in Strongly Correlated Systems – Theoretical Methods (Springer, 2012).
G. Li, W. Hanke, A. N. Rubtsov, S. Bäse, M. Potthoff, Phys. Rev. B 80, 195118 (2009).