Abstract
A model of the energy barrier of a molecule between two orientational states in the C60 crystal, which depends on the neighboring molecules, is first proposed. Based on this model, the orientational relaxation of C60 molecules around 90 K was simulated with the Monte Carlo method. The simulation results show that the relaxation is slightly non-exponential and can fit the Kohlrausch-Williams-Watts (KWW) function with the non-exponential factor β = 0.962 ± 0.002, which is equal to the experimental data that has not been explained before.