SIMILARITY LAWS AND THERMODYNAMIC QUANTITIES FOR FULLERITE C-60

The crystal structure of solid fullerite C-60 at temperatures exceedin g 260 K is the face centered cubic one. The intermolecular interaction in this crystal is short range so each C-60 molecule interacts only w ith the nearest neighbors. Substances having the mentioned features fo rm a class of those with some common properties. Thus the thermodynami c behavior of substances belonging to this class is governed by simila rity laws in accordance with which the thermodynamic parameters are di mensionless functions of quantities constructed of the molecular mass mu, temperature T, well depth in the intermolecular interaction potent ial D and equilibrium intermolecular distance R(o). One of these simil arity laws has been used to process known data related to the pressure vapor temperature dependences for fullerite C-60. This permits a refi nement 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 sim ilarity laws for those fullerite thermodynamic parameters for which ex perimental data are available. The fulfilment of similarity laws permi ts an estimation of the critical parameters, melting and boiling tempe ratures, bulk modulus and also the Debye temperature for fullerite. Th e obtained data are analyzed in terms of the possibility of the existe nce of fullerene in the liquid state.