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 ${\varphi }^4$ 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.

• Received 24 December 2019
• Revised 17 May 2020
• Accepted 21 May 2020

DOI:https://doi.org/10.1103/PhysRevB.101.235414