The orientational potential in solid C60

Numerous experimental findings indicate that the orientational potential in solid C-60 is much stiffer than was anticipated from the nearly spherical shape of the C-60 molecule and the rather large intermolecular distance - a fact, which remains to be properly understood. In this review we summarize experimental studies which allow one to extract information on the orientational potential. The experimental results are contrasted with predictions from various empirical potentials proposed in the literature. Special emphasis is laid on X-ray and neutron diffuse scattering results and how these results can be exploited to further our knowledge on the orientational potential.