The fluid-lattice gas isomorphism with application to liquid-vapor equilibrium in physisorbed monolayers
Year: 2026
Type: preprint
Abstract: Liquid-gas equilibrium is described using a pair of Ising-like thermodynamic variables. The first is a combination of density and energy fields that is even under phase coexistence, derived from the Gibbs-Duhem and Clausius-Clapeyron relations. The second is the normalized density deviation $M=ρ/ρ_d-1$, which distinguishes the coexisting phases and serves as an odd ordering variable. Combining these variables with the empirical linearities of the binodal diameter and the Zeno line leads to a projective mapping between continuum-fluid and lattice-gas states. The implications of such mapping are tested against coexistence-density and saturation pressure data for the two-dimensional Lennard-Jones fluid, as well as physisorbed molecular monolayers of simple molecular fluids like argon and methane. Finally, a heuristic microscopic interaction-variable formulation that motivates continuous fluids versus lattice model description is also discussed.
Source: arXiv (Cornell University)
Authors: Shevchenko, Lev, Kulinskii, Volodymyr
Institution: Odesa I. I. Mechnikov National University
Language: English
Subfield: Physical and Theoretical Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7164031029