Measures of Fluctuations for a Liquid Near Critical Drying

Abstract

We investigate density fluctuations in a liquid close to a solvophobic substrate at which a surface critical drying transition occurs. Using classical density functional theory, we determine three measures of the spatial extent and strength of the fluctuations, i.e., the local compressibility ${\chi }_{\mu }(z)$, the local thermal susceptibility ${\chi }_T(z)$ and the reduced density ${\chi }_{\ast }(z)$; $z$ is the distance from the substrate. Whilst the first measure is frequently used, the second and third were introduced very recently by Eckert et.al., Phys. Rev. Lett. 125, 268004 (2020). For state points in the critical drying regime, all three measures, each scaled by its bulk value, exhibit very similar forms and the ratio of ${\chi }_T(z)$ to ${\chi }_{\mu }(z)$, for fixed $z$ in the vapour-liquid transition region, is constant. Using a scaling treatment of surface thermodynamics we show that such behaviour is to be expected on general grounds.

7 pages, 3 figures. Accepted by Physical Review E

References in corpus (5)

• A unified description of hydrophilic and superhydrophobic surfaces in terms of the wetting and drying transitions of liquids
• The Local Compressibility of Liquids near Non-Adsorbing Substrates: A Useful Measure of Solvophobicity and Hydrophobicity?
• Critical Drying of Liquids
• Drying and Wetting Transitions of a Lennard-Jones Fluid: Simulations and Density Functional Theory
• Layering Transitions and Solvation Forces in an Asymmetrically Confined Fluid

Cited by in corpus (5)

• Understanding the physics of hydrophobic solvation
• Why hyperdensity functionals describe any equilibrium observable
• Local measures of fluctuations in inhomogeneous liquids: Statistical mechanics and illustrative applications
• Gauge invariance and hyperforce correlation theory for equilibrium fluid mixtures
• Metadensity functional learning for classical fluids: Regularizing with pair correlations