Symmetry-based analysis of the electron-phonon interaction in graphene

Abstract

Symmetry-based analysis of the electron-phonon interaction in graphene is performed. Some nontrivial physical properties of graphene are shown to be direct consequence of symmetry, independent on the applied dynamical model. Namely, it is found that there are vibronically uncoupled non symmetric modes which thus might be responsible for the stability of the honeycomb lattice. Symmetry also predicts vanishing of the electron-phonon interaction for quite a number of the normal displacements. Consequently, lattice dynamics along these degrees of freedom is governed by the ion repulsion which leads to the anharmonic terms, being linear in absolute elongation. In particular, this effect is attributed to the K and G{cyrillic} points of the Brillouin zone, giving insight into origin of the Kohn anomaly. The results are further numerically confirmed within full and tight-binding density functional calculations and force constants model. © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.