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DS: Fachverband Dünne Schichten
DS 50: Frontiers of Electronic Structure Theory: Focus on Topology and Transport V
(Joint session of DS and O, organized by O)
DS 50.8: Vortrag
Donnerstag, 10. März 2016, 16:45–17:00, H24
Ab-initio calculation of Raman spectra of graphene-based materials — •Albin Hertrich, Caterina Cocchi, Pasquale Pavone, and Claudia Draxl — Department of Physics, Humboldt-Universität zu Berlin, Germany
Raman scattering is an important non-destructive method for characterizing carbon-based materials. The main features of experimental Raman spectra of pristine graphene and graphite are the first-order G-band at ≈1580 cm−1 and the dispersive second-order 2D-band at ≈2700 cm−1. We calculate first- and second-order Raman spectra fully ab-initio using the full-potential all-electron DFT package exciting [1], which allows for the calculation of both phonon dispersion, within the frozen-phonon approximation, and frequency-dependent dielectric tensors, from time-dependent DFT and the Bethe-Salpeter equation. In our approach [2], we expand the dielectric tensor with respect to the phonon normal coordinates. By taking its derivatives and by computing vibrational matrix elements, we calculate Raman scattering intensities. Applying this scheme to monolayer graphene, bilayer graphene, and graphite, we obtain the G-band in good agreement with experiment [3]. Furthermore, we explore the influence of both the stacking sequence and the laser energy on the 2D-band.
[1] A. Gulans et al., J. Phys.: Condens. Matter 26, 363202 (2014).
[2] C. Ambrosch-Draxl et al., Phys. Rev. B 65, 064501 (2002).
[3] A. C. Ferrari et al., Phys. Rev. Lett. 97, 187401 (2006).