SurfaceScience21 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 53: Poster Session IV: Poster to Mini-Symposium: Frontiers of electronic-structure theory I

O 53.6: Poster

Dienstag, 2. März 2021, 13:30–15:30, P

Nonadiabatic renormalization of electron-phonon interaction in graphene-based materials — •Nina Girotto and Dino Novko — Institute of Physics, Zagreb, Croatia

Some of the most prominent features of two-dimensional (2D) materials issue from electron-phonon coupling (EPC) and are easily tailored by strain and doping. Phonon-mediated superconductivity is expected in a variety of 2D materials, and because the transition temperature within the Bardeen-Cooper-Schrieffer (BCS) theory increases with increasing EPC, tailoring EPC provides a recipe for a more feasible realization of superconductors. Here, we present density-functional-theory (DFT) calculations of EPC properties of doped 2D systems, specifically highly-doped graphene and hole-doped graphane. Doping equalizes the energy scales of electron transitions and phonon frequencies, but using the adiabatic Born-Oppenheimer approximation, DFT assumes nuclear and electronic motion can be separated. We show that the mentioned approximation is not applicable on studied systems, since the adiabatically obtained phonon spectrum is at significant variance with the one containing nonadiabatic corrections. Nonadiabatic renormalization greatly modifies the EPC strength, which in turn alters the superconducting transition temperature prediction, rendering its calculation more reliable. The importance of including dynamical corrections is indisputable and care should be taken when neglecting nonadiabatic effects as they have a huge impact not only on the magnitude of the EPC strength and the transition temperature, but also on the qualitative understanding of the system in question.