The thermodynamics of Lennard-Jones systems

A multiple disordering scaling is suggested for describing different aggregate states of Lennard-Jones systems, which enables one to explain the high value of the configurational entropy of liquefied inert gases at the triple point and provide for the transition from the crystalline to liquid and gaseous states. The free energy and pressure of a system after scaling are calculated using the generalized nearest neighbor approximation and depend on the disordering parameter. Small values of this parameter correspond to the condensed states (liquid and solid). When the disordering parameter tends to unity, an asymptotically exact equation of state for rarefied gas in an approximation of the second virial coefficient is derived. For intermediate values of this parameter, it is possible to construct curves of phase equilibria, including the triple and critical points, which fit the experimental data.