Stable configurations of C_(20) and C_(28) encapsulated in single wall carbon nanotubes

摘要

The stable configurations of small fullerenes (C20 and C_(28) encapsulated inside single wall carbon nanotubes (SWNTs) of different diameters were investigated by molecular dynamics simulations. The interactions between carbon atoms were described by a combination of the many-body Brenner potential with the Lennard-Jones (LJ) potential. We observed that the filling of small fullerenes into nanotubes with diameters larger than 10.85 A ((8, 8) SWNT) is an exothermic process. During the annealing process the fullerenes arrange themselves into complex phases, which may be one-(chain), two-(zigzag) or three-dimensional, depending on the tube diameter. This tube size dependence is very similar to that of C_(60), which has been experimentally observed. A comparison with the prediction of the hard-sphere model also finds a satisfactory level of consistency, indicating the dense packing nature of fullerene configurations in SWNTs.