Regensburg 2022 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 16: Correlated Electrons: Method Development
TT 16.8: Vortrag
Mittwoch, 7. September 2022, 11:45–12:00, H10
Matrix-product-state-based band-Lanczos solver for quantum cluster approaches — Sebastian Paeckel1,2, Thomas Köhler3, Salvatore R. Manmana4, and •Benjamin Lenz5 — 1Arnold Sommerfeld Center of Theoretical Physics, University of Munich, Germany — 2Munich Center for Quantum Science and Technology (MCQST), Munich, Germany — 3Department of Physics and Astronomy, Uppsala University, Sweden — 4Institute for Theoretical Physics, Georg August University of Göttingen, Germany — 5Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Sorbonne University, Paris, France
We present a matrix-product-states-based band-Lanczos method as a solver for quantum cluster techniques. Based on a traditional band-Lanczos technique for the calculation of the cluster Green’s function, we introduce and motivate different convergence criteria and discuss their impact on the stability of the results at the example of the variational cluster approximation. The capabilities of this method to calculate the self-energy functional are demonstrated for Hubbard-like models on different cluster geometries. Finally, we show a finite-size scaling of order parameters using cluster sizes, which are out of reach for traditional exact-diagonalization-based solvers.