Preferable Orientations of Interacting C_60 Molecules inside Single Wall Boron Nitride Nanotubes

This work focuses on the preferable orientation analysis of the hybrid system where the C_60 molecules are encapsulated inside the boron nitride nanotubes by using the two-molecule model. The low-energy state can be acquired in the contour map, which provides the visual information of the systematical van der Waals interaction potential for the C_60 molecules adopting different orientations. Our results show that the C_60 molecules exhibit the preferred pentagon and hexagon orientations with the tube's diameter smaller and larger than 13.55 ?, respectively. The preferred two-bond orientation obtained in the single-molecule model is absent in this study, indicating that the intermolecular interaction of adjacent C_60 molecules plays an important role in the orientational behaviors of this peapod structure.