ORIENTATIONALLY ORDERED STATES IN SOLID C-60

We study the orientational ordering of the fullerene molecules in solid C60 with a phenomenological model proposed by Lu, Li, and Martin [Phys. Rev. Lett. 68, 1551 (1992)]. It is shown that the energy of a particular configuration is sensitive to the bond length of the fullerene molecule and there is an orientation that might explain the orientational disorders in solid C60. Also, the experimentally observed superstructure is investigated. Numerical calculations show that the orientational ordering of the fullerene molecules will induce structural deformation in the superstructure. © 1995 The American Physical Society.