Room temperature Peierls distortion in small radius nanotubes

TL;DR

This study uses ab initio simulations to explore phonon behavior and electron-phonon interactions in small diameter nanotubes, revealing Peierls transitions at room temperature and implications for superconductivity.

Contribution

It demonstrates Peierls transitions in small nanotubes at room temperature and clarifies the role of phonons and electron-phonon coupling in these phenomena.

Findings

Peierls transition occurs above room temperature in small nanotubes.

Electron-phonon coupling is mainly due to phonons at q=2k_F.

Coupling strength increases as nanotube diameter decreases.

Abstract

By means of {\it ab initio} simulations, we investigate the phonon band structure and electron-phonon coupling in small 4-\AA diameter nanotubes. We show that both the C(5,0) and C(3,3) tubes undergo above room temperature a Peierls transition mediated by an acoustical long-wavelength and an optical $q=2k_F$ phonons respectively. In the armchair geometry, we verify that the electron-phonon coupling parameter $\lambda$ originates mainly from phonons at $q=2k_F$ and is strongly enhanced when the diameter decreases. These results question the origin of superconductivity in small diameter nanotubes.