(331aa) Friction Forces between Carbon Nanotube Walls with Deffects

Molecular Dynamics simulations were carried out to study the friction forces between two concentric carbon nanotube walls. The main contribution to the friction forces between two concentric nanotubes are located at the ends of the outer nanotube. At the center of the nanotube, the friction forces are not significant because the intermolecular forces are almost zero in the axial direction because of the symmetry of the system. The system consisted of a two-wall carbon nanotube with chiral conformation (7,0)/(9,9) under periodic conditions on the axial axis. The defects studied were the Stone-Wales and vacancies. We find that these defects have an important contribution to the friction forces at the center of the nanotube because they brake the symmetry of the system.