Hard sphere-like dynamics in a non hard sphere liquid

TL;DR

This study reveals that the collective dynamics of liquid Gallium near melting point can be effectively described by Enskog's kinetic theory, despite its structural deviations from a hard-sphere model, highlighting the theory's broader applicability.

Contribution

The paper demonstrates that Enskog's kinetic theory accurately describes the dynamics of a non hard-sphere, partially covalent liquid like Gallium.

Findings

Enskog's theory applies to liquid Gallium's dynamics.

Structural deviations do not hinder the theory's applicability.

Dynamics are well described by the extended heat mode approximation.

Abstract

The collective dynamics of liquid Gallium close to the melting point has been studied using Inelastic X-ray Scattering to probe lengthscales smaller than the size of the first coordination shell. %(momentum transfers, $Q$, $>$15 nm$^{-1}$). Although the structural properties of this partially covalent liquid strongly deviate from a simple hard-sphere model, the dynamics, as reflected in the quasi-elastic scattering, are beautifully described within the framework of the extended heat mode approximation of Enskog's kinetic theory, analytically derived for a hard spheres system. The present work demonstrates the applicability of Enskog's theory to non hard- sphere and non simple liquids.