# Dresden 2017 – wissenschaftliches Programm

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# O: Fachverband Oberflächenphysik

## O 88: Electronic Structure Theory: New Concepts and Developments in Density Functional Theory and Beyond - VI

### O 88.9: Vortrag

### Donnerstag, 23. März 2017, 12:30–12:45, GER 38

*Ab-initio*** study of the Raman spectra of strained graphene** — •Albin Hertrich, Caterina Cocchi, Pasquale Pavone, and Claudia Draxl — Department of Physics, Humboldt-Universität zu Berlin, Germany

Raman spectroscopy is an important non-destructive method for characterizing graphene-based materials.
The main features of Raman spectra of pristine graphene are the first-order
G-band at ≈ 1580 cm^{−1} and the dispersive second-order 2D-band at ≈ 2700 cm^{−1}.
In this work, we perform a systematic analysis on the effect
of strain on both bands.
All calculations are done
using
the full-potential all-electron code `exciting` [1].
Phonon properties are computed within the frozen-phonon approximation, the frequency-dependent dielectric tensor within the random-phase approximation.
Raman-scattering intensities are calculated from vibrational matrix elements and derivatives of the dielectric tensor with respect to the phonon normal coordinates [2].
Under biaxial strain both Raman bands are shifted, while uniaxial strain leads to a splitting of the G-band by lifting the degeneracy of the optical in-plane Γ-point phonons.
Further, we explore the effect of different types of inhomogeneous strain on the optical phonon frequencies and Raman-scattering intensities.

[1] A. Gulans *et al*., J. Phys.: Condens. Matter **26**, 363202 (2014).

[2] C. Ambrosch-Draxl *et al*., Phys. Rev. B **65**, 064501 (2002).