The Line of the Unit Compressibility Factor (Zeno-Line) for Crystal States

Hard-core attractive Yukawa fluid global isomorphism with the lattice gas model

In this work, we study the global isomorphism between the liquid–vapor equilibrium of the hardcore attractive Yukawa fluid (HCAYF) and that of the Lattice Gas (LG) model of the Ising-like type. The applicability of the global isomorphism transformation and the dependence of its parameters on the screening length of the Yukawa potential are discussed. These parameters determine both the slope of the rectilinear diameter of the liquid–vapor binodal and the Zeno-element, which are the core ingredients of the fluid–LG isomorphism. We compare the Zeno-element parameters with the virial Zeno-line parameters, which are commonly used in the literature for the formulation of generalized law of the correspondent states. It is demonstrated that the Zeno-element parameters appear to be sensitive to the liquid state instability when the interaction potential becomes too short-ranged, while the virial ones do not show any peculiarities connected with this specific of the HCAYF.

The Line of Ideal Isothermal Compressibility

We have considered the line along which the values of the isothermal compressibility of a system are the same as they would be for an ideal gas. It was called the κ_T line. Various substances and models have been studied with the use of the multi-parameter equations of states, implemented in REFPROP (Lemmon, E. W.; Bell, I. H.; Huber, M. L.; McLinden, M. O. NIST standard reference database 23: Reference fluid thermodynamic and transport properties-REFPROP, version 10.0 (National Institute of Standards and Technology, 2018)), and numerical simulations, respectively. It is shown that in the reduced variables, all κ_T lines can be described by the same relation following from the van der Waals equation. This similarity appears to be valid even for the systems with non-straight Zeno lines. Deviations within ∼5% are observed only near the binodals.