Molecular dynamics of axial interwall van der Waals force and mechanical vibration of double-walled carbon nanotubes

Abstract

In the first part of this study, the axial interwall van der Waals (vdW) interaction forces of Double-Walled Carbon nanotubes (DWCNTs) are calculated using the Molecular Dynamics (MD) method. The axial vdW forces, including Leonard-Jones forces, are simulated for different chiralities to investigate the effects of the carbon atoms arrangement of DWCNTs on the axial interwall vdW forces using six pairs of DWCNTs. The results show the maximum axial vdW forces for the zigzag DWCNTs. In the second part of this study, the axial vibrations of DWCNTs are calculated considering the effects of axial interwall vdW forces. These forces are modeled by linear springs in which their stiffness values (force per unit length per unit of displacement) are approximated based on the vdW forces obtained in the first part of this study. The equations of motion are analytically derived and solved for DWCNTs. The natural frequencies of axial vibrations are validated by the classical model. Consideration of the axial interwall vdW forces of DWCNTs had considerable influence on the natural frequencies of axial vibration. This impact is intensified by enhancement of DWCNT length, especially in the first vibration mode (Up to 49%).