Berlin 2024 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 108: Electronic Structure Theory II
O 108.1: Vortrag
Freitag, 22. März 2024, 10:30–10:45, MA 043
Downfolding approaches to electron-phonon coupling — •Jan Berges1, Nina Girotto2, Arne Schobert3, Erik van Loon4, Michael Sentef1, Sergey Brener3, Mariana Rossi5, Tim Wehling3, Samuel Poncé6,7, and Nicola Marzari8,1 — 1University of Bremen, Germany — 2Institute of Physics, Zagreb, Croatia — 3University of Hamburg, Germany — 4Lund University, Sweden — 5MPI for the Structure and Dynamics of Matter, Hamburg, Germany — 6ETSF, UCLouvain, Belgium — 7WEL Research Institute, Wavre, Belgium — 8EPFL, Lausanne, Switzerland
Despite the success of density-functional perturbation theory (DFPT), the simulation of electron-phonon interactions in materials remains challenging, especially for large systems or in presence of strong correlations. We address this problem by downfolding it to effective low-energy models, using localized representations in the basis of Wannier functions. Based on data from DFPT, this allows us to obtain phonon frequencies at high precision and low computational cost via corrections to the static phonon self-energy [Phys. Rev. X 13, 041009 (2023)]. A generalization beyond the harmonic approximation is possible, providing free energies, forces, and force constants for structurally distorted systems on supercells, based on DFPT data for the primitive cell of the undistorted system alone. This is an ideal platform for the study of charge-density waves (CDWs) and polarons. We apply it to perform molecular-dynamics simulations [arXiv:2303.07261] and to calculate phonon dispersions [Nano Lett., in press (2023), arXiv:2307.13791] for two-dimensional transition-metal dichalcogenides in the CDW phase.
Keywords: Phonons; Electron-Phonon Interaction; 2D Materials; Density-Functional Theory; Downfolding