van der Waals interaction in nanotube bundles : consequences on vibrational modes

TL;DR

This paper models van der Waals interactions in carbon nanotube bundles, revealing how these forces influence vibrational modes and breathing frequencies, with implications for understanding nanotube bundle properties.

Contribution

It introduces a continuum pair-potential approach combined with tight-binding calculations to analyze vibrational modes in nanotube bundles, highlighting the effect of bundling on breathing mode frequencies.

Findings

Intertube vibrational modes range from 5 to 60 cm^{-1}

Breathing mode frequency increases by ~10% in bundles

Slight chiral dependence of breathing mode frequency

Abstract

We have developed a pair-potential approach for the evaluation of van der Waals interaction between carbon nanotubes in bundles. Starting from a continuum model, we show that the intertube modes range from $5 cm^{-1}$ to $60 cm^{-1}$. Using a non-orthogonal tight-binding approximation for describing the covalent intra-tube bonding in addition, we confirme a slight chiral dependance of the breathing mode frequency and we found that this breathing mode frequency increase by $\sim$ 10 % if the nanotube lie inside a bundle as compared to the isolated tube.