Spectroscopic signatures of nonpolarons: the case of diamond
(2022) Physical Chemistry Chemical Physics — Vol. 24, n° 20, p. 12580-12591 (2022)
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- Authors
de Abreu, Joao C. 
Verstraete, Matthieu J.
- Abstract
- Polarons are quasi-particles made from electrons interacting with vibrations in crystal lattices. They derive their name from the strong electron-vibration polar interactions in ionic systems, that induce spectroscopic and optical signatures of such quasi-particles. In this paper, we focus on diamond, a nonpolar crystal with inversion symmetry which nevertheless shows interesting signatures stemming from electron-vibration interactions, better denoted ‘‘nonpolaron’’ signatures in this case. The (non)polaronic effects are produced by short-range crystal fields, while long-range quadrupoles only have a small influence. The corresponding many-body spectral function has a characteristic energy dependence, showing a plateau structure that is similar to but distinct from the satellites observed in the polar Fro¨hlich case. We determine the temperature-dependent spectral function of diamond by two methods: the standard Dyson–Migdal approach, which calculates electron–phonon interactions within the lowestorder expansion of the self-energy, and the cumulant expansion, which includes higher orders of electron–phonon interactions. The latter corrects the nonpolaron energies and broadening, providing a more realistic spectral function, which we examine in detail for both conduction and valence band edges.
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Citations
de Abreu, J. C., Nery, J. P., Giantomassi, M., Gonze, X., & Verstraete, M. J. (2022). Spectroscopic signatures of nonpolarons: the case of diamond. Physical Chemistry Chemical Physics, 24(20), 12580-12591. https://doi.org/10.1039/d2cp01012g (Original work published 2022)