Orientational ordering of solid C70

We investigate the ground state structures and orientational ordering of face-centered-cubic, hexagonal-close-packed, rhombohedral, orthorhombic, and monoclinic lattices of solid C70. We find that the calculated lattice constants of the hexagonal phases and face-centered-cubic lattice are in excellent agreement with the observed experimental values and further provide the exact orientational ordering of the crystals. The driving force for the phase transformation of various orientational orderings is an effective contact area between C70 molecules. Phase transformation associated with orientational ordering is also discussed.