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O: Fachverband Oberflächenphysik

O 96: Poster Session VII: Poster to Mini-Symposium: Frontiers of electronic-structure theory IV

O 96.2: Poster

Thursday, March 4, 2021, 10:30–12:30, P

A Bethe-Salpeter equation and a GW approach with electron-phonon coupling: from exciton binding energies to charge mobilities. — •Paolo Umari — University of Padova, Padova, Italy

e have introduced a simple scheme in order to account for the coupling with longitudinal phonons within the first-principles Bethe-Salpeter approach based on many-body perturbation theory. This allows to evaluate the reduction of exciton binding energies observed in polar semiconductors. The electron-phonon coupling is modelled from the macroscopic dielectric response in the infrared which, in turn, is calculated through density functional perturbation theory. In this way, the additional computational cost determined by our method is negligible. I will first illustrate our approach in the case of bulk ZnS and show how the excitonic series of bulk Cu2O is well reproduced[1]. The method could clarify the role of dielectric screening in hybrid perovskites yielding exciton binding energies in agreement with experiment[2]. Finally, I will discuss the extension of our method to GW calculations and I will show how the renormalisation of band-gaps and effective masses, and electron and hole mobilities can be easily calculated. Results for the hybrid perovskite MAPbI3 are in agreement with the most accurate calculations which include explicitly the coupling with phonons.

[1]L. Adamska and P. Umari, Phys. Rev B accepted (2021) [2]P. Umari, E. Mosconi, F. De Angelis, J. Phys. Chem. Lett. 9, 620 (2018).