Structural precursor to freezing: An integral equation study

TL;DR

This study uses an advanced integral equation approach to analyze the structural features in dense fluids that precede freezing, showing that certain radial distribution function features are not solely due to packing effects.

Contribution

It demonstrates that the shoulder in the radial distribution function near freezing can be explained by local packing constraints and is influenced by attractive interactions, not just high-density packing.

Findings

Shoulder in radial distribution function correlates with broadened coexistence region.

Short-range attraction broadens the fluid-solid transition.

Structural precursor features are not solely due to packing effects.

Abstract

Recent simulation studies have drawn attention to the shoulder which forms in the second peak of the radial distribution function of hard-spheres at densities close to freezing and which is associated with local crystalline ordering in the dense fluid. We address this structural precursor to freezing using an inhomogeneous integral equation theory capable of describing local packing constraints to a high level of accuracy. The addition of a short-range attractive interaction leads to a well known broadening of the fluid-solid coexistence region as a function of attraction strength. The appearence of a shoulder in our calculated radial distribution functions is found to be consistent with the broadened coexistence region for a simple model potential, thus demonstrating that the shoulder is not exclusively a high density packing effect.