Criticality of a liquid–vapor interface from an inhomogeneous integral equation theory

Abstract

A microscopic theory is developed to study the liquid–vapor interfacial properties of simple fluids with ab initio treatment of the inhomogeneous two-body correlation functions, without any interpolation. It consists of the inhomogeneous Ornstein–Zernike equation coupled with the Duh–Henderson–Verlet closure and the Lovett–Mou–Buff–Wertheim equation. For the liquid–vapor interface of the Lennard-Jones fluid, we obtained the density profile and the surface tension, as well as their critical behaviour. In particular, we identified non-classical critical exponents. The theory accurately predicts the phase diagram and the interfacial properties in a very good agreement with simulations. We also showed that the method leads to true capillary-wave asymptotics in the macroscopic limit.