Theoretical study of the saturated vapor pressure and enthalpy of sublimation ofsfullerite

The saturated vapor pressure and the enthalpy of sublimation of (Formula presented) has been calculated using a virial expansion for the gas and the correlative method of an unsymmetrized self-consistent field for the crystal, from the equilibrium point with the orientationally ordered phase up to the spinodal point estimated as (Formula presented) ≈1917 K. The Girifalco intermolecular potential is utilized. The dependence (Formula presented) (1/T) is close to a linear one, while Δ(Formula presented) decreases from 172.9 to 140.5 kJ/mole. The results are in good agreement with experimental data available between 600 and 990 K. Scaling of values obtained earlier for Ar gives an estimate for the triple point of the (Formula presented) fullerene: (Formula presented) ≈1460 K, (Formula presented) ≈740 Torr. © 1997 The American Physical Society.