  Depending on the temperature, the C70 solid crystallizes in several
structures. At high temperature (T > 340K), the ellipsoidal C70 molecule
rotates freely in all directions and may be treated as a uniform thick
spherical shell with inner and outer radii as the minimum and the maximum
distance of C-atom from the center of the molecule. At lower temperatures the
free rotations of molecules freeze out. We have calculated the lattice
parameters, energies and bulk modulus at the minimum energy configuration of
fcc and hcp phase of pure C70 solid at high temperature using a simple model
based on atom-atom potential.
