The possible orientations in solid C60 were studied by using the model
of classical molecular interaction. An orientational dynamics' model
was developed to calculate the phase transition temperature of the obs
erved face-centre-cubic phase to simple-cubic phase. The calculated tr
ansition temperature T(c) = 250K, and its pressure dependence dT(c)/dp
= 11.4K / 10(8)Pa agrees well with the experiments. Below T(c), the g
lassy transition temperature T(g) = 93K was also predicted correctly.