Vibrational properties of single-wall nanotubes and monolayers of hexagonal BN

TL;DR

This paper provides a comprehensive analysis of the vibrational properties of BN single-walled nanotubes and monolayers using a combined Tight-Binding and electrostatic model, offering detailed phonon and elastic data.

Contribution

It introduces a detailed computational study of BN nanotubes and monolayers, including phonon spectra and elastic constants, with a comparison of nanotube vibrational modes to zone-folding predictions.

Findings

Good agreement between nanotube phonon frequencies and zone-folding model.

Detailed phonon band structure and vibrational density of states for BN monolayer.

Behavior of optically active modes as a function of nanotube structure.

Abstract

We report a detailed study of the vibrational properties of BN single-walled nanotubes and of the BN monolayer. Our results have been obtained from a well-established Tight-Binding model complemented with an electrostatic model to account for the long-range interactions arising from the polar nature of the material, and which are not included in the Tight-Binding model. Our study provides a wealth of data for the BN monolayer and nanotubes, such as phonon band structure, vibrational density of states, elastic constants, etc. For the nanotubes we obtain the behavior of the optically active modes as a function of the structural parameters, and we compare their frequencies with those derived from a zone-folding treatment applied to the phonon frequencies of the BN monolayer, finding general good agreement between the two.