The Zeno line and binodal for Ga

Parameters of the Liquid-Gas-State Triangle for Hard-Core Attractive Yukawa Fluids

We discuss the triangle of the liquid-gas concept within the fluid-lattice gas isomorphism approach and the Zeno-element, taking the hard-core Yukawa fluid (HCAYF) as an example. The applicability of such an isomorphism is demonstrated by the symmetrization of binodals with mapping onto the Ising model coexistence curve. We show that the parameters of the isomorphism transformation reflect the liquid-phase instability for hard-core Yukawa potential and its generalization. We also provide a simple mean-field estimate for the parameter z of the fluid-lattice gas transformation and use it to obtain the locus of the critical point.

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.

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

We study the behavior of the line of the unit compressibility factor (Zeno-line) in crystalline states. We used the Lennard-Jones system, experimental P-V-T data for a number of substances, and the Debye model. We found that, contrary to the case of the liquid states, the Zeno-line in a crystal is not a straight line at the density-temperature plane. However, the corresponding pressure-temperature dependence appears to be quasi-linear. As a result, this line in the solid state can be defined by the only one point where the Zeno-line crosses the melting curve.