Molecular dynamics study of double-walled carbon nanotubes for nano-mechanical manipulation

Double-walled carbon nanotubes (DWNTs) are expected to be useful as elements in nano-mechanical systems such as nanobearings and nanosliders. A molecular dynamics Simulation is carried out to estimate the relative motion between the inner and outer tubes. The force required to pull the inner tube out of the outer tube is evaluated quantitatively by pulling the inner tube under a constant velocity for DWNTs with various inter-tube spacings and chiralities. When the inner tube is pulled under smaller constant force, the inner tube vibrates inside the outer tube without being pulled out, and an energetics is applied to explain the critical force and vibrational amplitude. The constant force induces not only vibration along the tube axis but also rotation around the tube axis, which indicates the possibility of creating a slider crank mechanism using a DWNT.