Regensburg 2022 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 28: Organic Molecules at Surfaces 3: Theory
O 28.2: Vortrag
Dienstag, 6. September 2022, 10:45–11:00, S051
Substrate enhanced Jahn-Teller effect in single molecule junctions — •Moritz Frankerl1, Laerte Patera2,3, Thomas Frederiksen4, Jascha Repp3, and Andrea Donarini1 — 1Institute for Theoretical Physics, University of Regensburg — 2Catalysis Research Center, Technical University of Munich — 3Institute of Experimental and Applied Physics, University of Regensburg — 4Donostia International Physics Center (DIPC), Spain
The stabilization of several charge states of single molecules deposited on non-conductive NaCl films [1] allows to map out the electronic transition between different charge states by means of single-electron alternate-charging scanning tunneling microscopy [2].Copper-phthalocyanine (CuPc) revealed a Jahn-Teller splitting (JTS) of its doubly degenerate LUMOs upon charging and, more surprisingly, the occupation of the same LUMO for both electrons upon double charging. We show by DFT calculations complemented by a group-theoretical analysis how the JTS for CuPc in gas phase is not sufficient to explain this behavior. We propose, instead, a cooperation between molecule and substrate deformation which enhances the strength of the JT coupling. The result is based on a microscopic model of the electron-phonon coupling between the molecule and the underlying thick layer of NaCl. The magnitude of the obtained substrate-induced JTS highlights the impact of the substrate on the electronic configuration of charged molecules, far beyond the mere charge stabilization. [1] Fatayer S. et al., Nature Nanotechnology 13, 376-380(2018) [2] Patera L.L. et al., Nature 566, 245-248(2019)