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O: Fachverband Oberflächenphysik
O 82: Poster Session VI: Poster to Mini-Symposium: Frontiers of electronic-structure theory III
O 82.1: Poster
Wednesday, March 3, 2021, 13:30–15:30, P
Diagrammatic Monte Carlo study of the acoustic lattice polaron — •Thomas Hahn1, Andrey Mishchenko2,3, Naoto Nagaosa2, and Cesare Franchini1,4 — 1Faculty of Physics, Center for Computational Materials Science, University of Vienna, A-1090 Vienna, Austria — 2RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan — 3National Research Center Kurchatov Institute, 123182 Moscow, Russia — 4Dipartimento di Fisica e Astronomia, Università di Bologna, 40127 Bologna, Italy
The Diagrammatic Monte Carlo (DMC) method is used to study an electron interacting with acoustic phonons via the deformation potential. For the first time, we obtain unbiased results for the acoustic polaron in a realistic condensed matter discrete lattice model and resolve self-contradictory conclusions from previous studies based on the continuum approximation. We present accurate numerical results for the ground state energy, effective mass, quasiparticle weight and the structure of the phonon cloud of the polaron. The most interesting data is obtained for excited states in the parameter range of the transient region between the weak and strong coupling regime. The unique structureless shape of the incoherent part of the spectral function and the flat background of the optical conductivity allows us to follow the behavior of excited states, whose studies are hindered in optical polaron models. We show that the behavior of the excited states in the spectral function is different from what is seen in the optical conductivity. This confirms the different nature of the excited states observed in these different probes of the excited spectra of the polaron.