Similarity laws and thermodynamic quantities for fullerite C60

The crystal structure of solid fullerite C60 at temperatures exceeding 260 K is the face centered cubic one. The intermolecular interaction in this crystal is short range so each C60 molecule interacts only with the nearest neighbors. Substances having the mentioned features form a class of those with some common properties. Thus the thermodynamic behavior of substances belonging to this class is governed by similarity laws in accordance with which the thermodynamic parameters are dimensionless functions of quantities constructed of the mokecular mass μ, temperature T, well depth in the intermolecular interaction potential D and equilibrium intermolecular distance Ro. One of these similarity laws has been used to process known data related to the pressure vapor temperature dependences for fullerite C60. This permits a refinement of the magnitude D = 0.257 + 0.01 eV known up to now with more uncertainty. This magnitude is used for checking the fulfilment of similarity laws for those fullerite thermodynamic parameters for which experimental data are available. The fulfilment of similarity laws permits an estimation of the critical parameters, melting and boiling temperatures, bulk modulus and also the Debye temperature for fullerite. The obtained data are analyzed in terms of the possibility of the existence of fullerene in the liquid state.