# Anomalous pressure behavior of tangential modes in single-wall carbon nanotubes

## TL;DR

This study investigates how Raman-active tangential modes in a single-wall carbon nanotube respond to hydrostatic pressure, revealing diverse behaviors linked to symmetry changes, using molecular dynamics and force constant models.

## Contribution

It introduces a detailed analysis of pressure effects on TMs in SWNTs, highlighting symmetry alterations as a key factor, which is a novel insight compared to prior studies.

## Key findings

- Pressure derivatives of TMs vary with pressure, showing distinct behaviors.
- Symmetry of the nanotube changes from D10h to D2h to C2h under pressure.
- Anomalous pressure behavior is linked to symmetry alterations.

## Abstract

Using the molecular dynamics simulations and the force constant model we have studied the Raman-active tangential modes (TMs) of a (10, 0) single-wall carbon nanotube (SWNT) under hydrostatic pressure. With increasing pressure, the atomic motions in the three TMs present obvious diversities. The pressure derivative of E1g, A1g, and E2g mode frequency shows an increased value (), a constant value (), and a negative value () above 5.3 GPa, respectively. The intrinsic characteristics of TMs consumedly help to understand the essence of the experimental T band of CNT. The anomalous pressure behavior of the TMs frequencies may be originated from the tube symmetry alteration from D10h to D2h then to C2h.

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Source: https://tomesphere.com/paper/0704.0977