Electron-vibration coupling induced renormalization in the photoemission spectrum of diamondoids.
The development of theories and methods devoted to the accurate calculation of the electronic quasi-particle states and levels of molecules, clusters and solids is of prime importance to interpret the experimental data. These quantum systems are often modelled by using the Born-Oppenheimer approximation where the coupling between the electrons and vibrational modes is not fully taken into account, and the electrons are treated as pure quasi-particles. Here, we show that in small diamond cages, called diamondoids, the electron-vibration coupling leads to the breakdown of the electron quasi-particle picture. More importantly, we demonstrate that the strong electron-vibration coupling is essential to properly describe the overall lineshape of the experimental photoemission spectrum. This cannot be obtained by methods within Born-Oppenheimer approximation. Moreover, we deduce a link between the vibronic states found by our many-body perturbation theory approach and the well-known Jahn-Teller effect.
Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, PO Box 49, H-1525 Budapest, Hungary.|Department of Atomic Physics, Budapest University of Technology and Economics, Budafoki út 8, H-1111 Budapest, Hungary.
Adam
http://orcid.org/0000-0002-3339-5470
A
Gali
Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, PO Box 49, H-1525 Budapest, Hungary.|Institute of Physics, Loránd Eötvös University, Pázmány Péter sétány 1/A, H-1117 Budapest, Hungary.
Tamás
T
Demján
Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, USA.|Institute for Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA.
Márton
M
Vörös
Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, PO Box 49, H-1525 Budapest, Hungary.|Department of Atomic Physics, Budapest University of Technology and Economics, Budafoki út 8, H-1111 Budapest, Hungary.
Gergő
G
Thiering
Aix-Marseille Université, CNRS, PIIM UMR 7345, 13397 Marseille, France.
Elena
E
Cannuccia
Institute for Material Science (ISM) of the National Research Council (CNR), Via Salaria Km 29.3, CP 10, 00016 Monterotondo Stazione, Italy.
Andrea
A
Marini