Implicit Phonon Shifts and Thermodynamical Properties of Rigid Carbon Nanotube Ropes

TL;DR

This paper models phonon shifts and thermodynamic properties of rigid carbon nanotube ropes using atom-atom potentials, providing insights into their behavior under pressure and comparing results with experimental data.

Contribution

It introduces a simple atom-atom potential model to analyze phonon shifts and thermodynamic properties of rigid carbon nanotube bundles under hydrostatic pressure.

Findings

Calculated phonon shifts of external modes in nanotube bundles.

Determined thermodynamic properties like thermal expansion and bulk modulus.

Compared theoretical results with experimental data.

Abstract

We calculate phonon shifts of external modes of a bunch of carbon nanotubes. A simple model based on atom-atom potential has been used to calculate the implicit anharmonicity in the phonons of carbon nanotube bundles having rigid tubes, with the assumption that under hydrostatic pressure only the intertube distance in the bunch varies. Such a model is important as long carbon nanotube ropes will be an extension of a fixed length ropes as is done here. Various bulk and thermodynamic properties like thermal expansion, bulk modulus and the Gruneisen constants and external phonon shifts which naturally enter into the calculation are also described and compared with the available data. The specific heat capacity has also been calculated.