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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 31: Organic Electronics and Photovoltaics II

CPP 31.2: Talk

Wednesday, March 20, 2024, 15:15–15:30, H 0110

Effective Electron-Vibration Coupling Constants by Ab Initio Methods — •Maximilian Franz-Xaver Dorfner and Frank Ortmann — TUM School of Natural Sciences, Technische Universität München, 85748 Garching b. München, Germany

This contribution is concerned with the analysis of different levels of theory for calculating the linear electron-phonon coupling constants. To bridge between density functional theory (DFT) and higher-level many-body approaches, we make use of the quasi-particle picture. Within this framework, we derive an effective quasi-particle linear coupling Hamiltonian, which describes the interaction of quasi-particles with phonons. We use this description to establish an approximate connection between the coupling constants calculated with DFT and higher-level many-body approaches by identifying the Kohn-Sham potential as an approximation to the static part of the self-energy. We determine the conditions under which a pragmatic DFT approach yields, in principle, the same coupling constants as a numerically much more expensive many-body approach. To test the theory, we finally compare the respective coupling constants for a few small molecules. The numerical results are found to be in good agreement with the presented theory.

Keywords: Electron-Phonon-Coupling; Fermi-Liquid Quasi-Particles; Density Functional Theory