Giant electron-phonon interactions in molecular crystals and the importance of non-quadratic coupling
Physical Review B
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Monserrat Sanchez, B., Engel, E., & Needs, R. (2015). Giant electron-phonon interactions in molecular crystals and the importance of non-quadratic coupling. Physical Review B, 92 (140302(R))https://doi.org/10.1103/PhysRevB.92.140302
We investigate electron-phonon coupling in the molecular crystals CH_4, NH_3, H_2O, and HF, using first-principles quantum mechanical calculations. We find vibrational corrections to the electronic band gaps at zero temperature of -1.97 eV, -1.01 eV, -1.52 eV, and -1.62 eV, respectively, which are comparable in magnitude to those from electron-electron correlation effects. Microscopically, the strong electron-phonon coupling arises in roughly equal measure from the almost dispersionless high-frequency molecular modes and from the lower frequency lattice modes. We also highlight the limitations of the widely used Allen-Heine-Cardona theory, which gives significant discrepancies compared to our more accurate treatment.
B.M. acknowledges Robinson College, Cambridge, and the Cambridge Philosophical Society for a Henslow Research Fellowship. E.A.E. and R.J.N. acknowledge financial support from the Engineering and Physical Sciences Research Council (EPSRC) of the UK [EP/K013688/1]. The calculations were performed on the Cambridge High Performance Computing Service facility and the Archer facility of the UK's national high-performance computing service (for which access was obtained via the UKCP consortium [EP/K013564/1]).
External DOI: https://doi.org/10.1103/PhysRevB.92.140302
This record's URL: https://www.repository.cam.ac.uk/handle/1810/251412
Attribution-NonCommercial 2.0 UK: England & Wales
Licence URL: http://creativecommons.org/licenses/by-nc/2.0/uk/