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TT: Fachverband Tiefe Temperaturen
TT 34: Correlated Electrons: Theory 2
TT 34.6: Vortrag
Donnerstag, 8. September 2022, 16:15–16:30, H23
Finite-temperature optical conductivity with density-matrix renormalization group methods for the Holstein polaron and bipolaron with dispersive phonons — •David Jansen1, Janez Bonča2,3, and Fabian Heidrich-Meisner1 — 1Institute for Theoretical Physics, University of Göttingen — 2J. Stefan Institute, Ljubljana — 3Faculty of Mathematics and Physics, University of Ljubljana
We compute the optical conductivity for the Holstein polaron and bipolaron with dispersive phonons at finite temperature using a matrix-product state based method. We combine purification [1], to obtain the finite-temperature states, together with the parallel time-dependent variational principle (pTDVP) [2] algorithm to compute the real time current-current correlation functions. The pTDVP algorithm utilizes local basis optimization [3] to efficiently treat the phononic degrees of freedom. For the polaron, we find that the phonon dispersion alters the optical conductivity at several temperatures in the weak, intermediate, and strong coupling regime. In the two first cases, we see that the spectrum goes from being continues to discrete when going from a downwards to a upwards phonon dispersion. In the strong coupling regime, the dispersion leads to a shift of the center of the spectrum. For the bipolaron, we study the effect of dispersion in both the weak and strong electron-phonon coupling regime, and thus see its influence on both a delocalized and a localized bipolaron.
This research was supported by the DFG via SFB 1073.
[1] Verstraete et al., Phys. Rev. Lett. 93, 207204 (2004)
[2] Secular et al., Phys. Rev. B 101, 235123 (2020)
[3] Zhang et al., Phys. Rev. Lett. 80, 2661 (1998)