Bushes of Nonlinear Normal Modes in Single-Layer Graphene

Abstract

In-plane vibrations in uniformly stretched single-layer graphene (space group P6mm), which are described by the Rosenberg nonlinear normal modes (NNMs) and their bushes, are studied with the aid of group-theoretical methods developed by authors in some earlier papers. It was found that only 4 symmetry-determined NNMs (one-dimensional bushes), as well as 14 two-dimensional bushes are possible in graphene. They are exact solutions to the dynamical equations of this two-dimensional crystal. The verification of group-theoretical results with the aid of ab initio simulations based on density functional theory is discussed.