Torsional behaviour of carbon nanotubes with abnormal interlayer distances

Atomistic simulations are performed to investigate the torsional behaviour of abnormal double-walled carbon nanotubes (DWCNTs) with an interlayer distance of less than 0.34 nm and carbon nanowires (CNWs) made of linear carbon-atom chain (C-chain) encapsulated inside single-walled carbon nanotubes (SWCNTs) subject to torsional motion. The interaction between atoms is modelled using the second-generation reactive empirical bond-order potential coupled with the Lennard-Jones potential. These simulations indicate that the effect of the van der Waals (vdW) interaction is more significant for abnormal DWCNTs than for normal DWCNTs. The critical torsional moments of abnormal DWCNTs are considerably enhanced compared with those of corresponding normal DWCNTs. It is worth noting that the critical torsional moment does not always increase with a decrease in the interlayer distance of DWCNTs. Numerical results also show that the torsional behaviours of CNWs are influenced dramatically by the radius of CNWs. Compared with those of corresponding SWCNTs, the critical torsional moment and the critical torsional angle of CNW increase in CNWs of radius less than 0.4 nm and decrease in (6, 6) and (11, 0) CNWs with large radius.