$\phi^4$ Theory Hamiltonian for Fluids: Application to the surface tension near the critical point

TL;DR

This paper develops a microscopic  field theory approach to accurately describe the surface tension of fluids near the critical point, emphasizing the importance of microscopic structure.

Contribution

It introduces a revised  theory incorporating microscopic fluid structure to predict surface tension near criticality, validated by numerical experiments.

Findings

Analytical expression for surface tension agrees with numerical data

Microscopic structure significantly influences critical surface tension behavior

Method applicable to small-volume systems in technological applications

Abstract

We show that the surface tension of fluid near the critical point may be correctly described by taking into consideration the microscopic structure of the system using a {\phi}4 field theory. We revise the theory of the surface tension near criticality to take into account a microscopic structure of the fluid. Focusing on the case of the Lennard-Jones fluid, we express the surface tension in terms of the compressibility of the reference hard-core system and its derivatives with respect to density. We demonstrate that the obtained analytical microscopic expression for the surface tension near the critical point is in a good agreement with numerical experiments, which emphasizes the impact of microscopic structure on the critical behavior of the surface tension in fluids. Our analysis provides a basis for studying the surface tension in small-volume systems important in many technological applications.