SKM 2021 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 9: Poster Session: Correlated Electrons

TT 9.29: Poster

Tuesday, September 28, 2021, 13:30–16:00, P

Spectral function of the Hubbard model using cluster perturbation theory — •Nicklas Enenkel¹, Peter Schmitteckert², and Markus Garst¹ — ¹Karlsruher Institut für Technologie, Karlsruhe, Deutschland — ²HQS - Quantum Simulations, Karlsruhe, Deutschland

The spectral function of the single band Hubbard model is calculated as part of a benchmark study using cluster perturbation theory (CPT). Within the framework of CPT, the Green function of a certain cluster of sites is first calculated numerically exactly, and, in a second step, the hopping of electrons between the clusters is treated in perturbation theory. Practically, however, a numerically reliable determination of the cluster Green function poses a challenge, and we compare various numerical approaches involving exact diagonalization, Chebychev expansion and equation of motion techniques. Results for the full spectral function are presented and discussed for the one- and two-dimensional Hubbard model.