Related Concept Videos
Van der Waals Equation
First, the attractive forces between molecules, which are stronger at higher densities and reduce the pressure, are considered by adding to the pressure a term equal to the square of the molar density multiplied by a positive coefficient a. Second, the volume...
Molecular Comparison of Gases, Liquids, and Solids
Real Gases: Effects of Intermolecular Forces and Molecular Volume Deriving Van der Waals Equation
Gauss's Law
Distillation: Vapor–Liquid Equilibria
Typical Model Studies
You might also read
Related Articles
Articles linked to this work by shared authors, journal, and citation graph.
Microscopic determination of correlations in the fluid interfacial region in the presence of liquid-gas asymmetry.
Related Experiment Video
Updated: Jan 6, 2026

Controlled Synthesis and Fluorescence Tracking of Highly Uniform PolyN-isopropylacrylamide Microgels
Published on: September 8, 2016
Correlation-function structure in square-gradient models of the liquid-gas interface: Exact results and reliable
1Department of Mathematics, Imperial College London, London SW7 2BZ, United Kingdom.
This study validates approximations for fluid interface correlations. These approximations accurately describe the structure factor and pair correlation function across all wave vectors, even near tricritical points.
Area of Science:
- Physical Chemistry
- Statistical Mechanics
- Soft Matter Physics
Background:
- Microscopic structure of density-density correlations in fluid interfaces is crucial for understanding interfacial phenomena.
- Previous work identified resonances in the local structure factor at specific parallel wave vectors (q) for short-ranged forces.
Purpose of the Study:
- To further investigate and validate approximations for the local structure factor and pair correlation function.
- To compare these approximations against analytically solvable models within square-gradient theory.
- To assess the accuracy of these approximations for interfacial systems, including those near tricritical points.
Main Methods:
- Comparison of approximations for local structure factor and pair correlation function.
- Analysis using three new analytically solvable models within square-gradient theory.
- Evaluation against numerical solutions of the Ornstein-Zernike equation for a model near a tricritical point.
Main Results:
- Approximations accurately describe the pair correlation function and structure factor across the entire wave vector spectrum.
- The approximations capture the crossover from Goldstone mode divergence (small q) to bulk-like behavior (large q).
- Approximations are exact for some potentials and highly accurate (within a few percent) for others, including near tricritical points.
Conclusions:
- The validated approximations provide a robust framework for understanding density-density correlations in fluid interfaces.
- These approximations are versatile, accurately describing interfacial behavior across various conditions, including near critical points.
- The findings offer a simplified yet accurate method for analyzing complex interfacial structures.

