Structure and phase transitions of single-wall carbon nanotube bundles under hydrostatic pressure

We have studied the structures of single-wall carbon nanotube bundles with and without hydrostatic pressure by using constant pressure molecular dynamics methods. The structure is found to be strongly dependent on the symmetry of the tubes, and only (6n, 6n) tubes could be assembled into an ideal hexagonal lattice. With increasing pressure, all tube lattices undergo a structure transition, while the transition pressure varies with the symmetry and radius of the tube.