Valence Force Model for Phonons in Graphene and Carbon Nanotubes

TL;DR

This paper introduces a new valence force model for sp^2 carbon interactions that accurately predicts phonon spectra in graphene and nanotubes, matching experimental and ab initio results, and applicable to distorted structures.

Contribution

A novel valence force model for sp^2 carbon systems that accurately reproduces phonon spectra and can be applied to distorted structures without assuming a fixed lattice.

Findings

Phonon spectrum of graphene matches experimental data

Breathing-mode energy of nanotubes agrees with measurements

Model applicable to distorted carbon structures

Abstract

Many calculations require a simple classical model for the interactions between sp^2-bonded carbon atoms, as in graphene or carbon nanotubes. Here we present a new valence force model to describe these interactions. The calculated phonon spectrum of graphene and the nanotube breathing-mode energy agree well with experimental measurements and with ab initio calculations. The model does not assume an underlying lattice, so it can also be directly applied to distorted structures. The characteristics and limitations of the model are discussed.