New Derived Perturbation‒Theory‒Based Regularity Using Yukawa Potential

Understanding of the molecular behavior of fluids is of the certain complexity at the molecular scale. So, the attention to the thermodynamics models and also describing equations of state the fluids is indispensible. In the present work, newly‒derived adjustable isotherm regularity [1-2] has been introduced for the variety of dense fluids, both compressed liquids and dense supercritical fluids, in the framework of average hard‒core Yukawa potential energy by recourse to liquid’s perturbation theory (TPT) [3]. The regularity predicts that the isotherm Z‒Zref is a linear function of reciprocal cube-power of density, where Z is the compression factor [4], Zref is the compression factor of reference system [5] defined in liquid’s TPT‒theory. The linear parameters are identified as interaction coefficients (the intercept A and the slope B) related to attraction only and both depend on temperature and also are used to evaluate the molecular parameters such as effective molecular diameter and Yukawa screening length. The p‒v‒T correlations of regularity were compared to the experimental data at the different range of temperature for the various ranges of dense fluids and the reasonable results were obtained. The results mirror the fact that the perturbation‒theory‒based regularity is valid merely for densities greater than Boyle density.