Theoretical treatment of anharmonicity of vibrational modes of single‐walled carbon nanotubes

Abstract We report a computational study, using the “moments method” [Y. Gao and M. Daw, Modell. Simul. Mater. Sci. Eng. 23 045002 (2015)], of the anharmonicity of the vibrational modes of single‐walled carbon nanotubes. We find that modes with displacements largely within the wall are more anharmonic than modes with dominantly radial character, except for a set of modes that are related to the radial breathing mode that are the most anharmonic of all. We also find that periodicity of the calculation along the tube length does not strongly affect the anharmonicity of the modes but that the tubes with larger diameter show more anharmonicity. Comparison is made with available experiments and other calculations.