A Kinetic Criterion for Stokes-Einstein Relation Breakdown Based on Effective Collisional Geometry

Zhen-Wei Wu

doi:10.1088/1674-1056/ae32ff

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arXiv · 2512.04364

A Kinetic Criterion for Stokes-Einstein Relation Breakdown Based on Effective Collisional Geometry

Zhen-Wei Wu

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Abstract

Here we propose a kinetic framework for interpreting the Stokes-Einstein (SE) relation breakdown in supercooled liquids by introducing an effective collision diameter, $d_{\mathrm{eff}}$, derived from transport data. Numerical simulation of a model CuZr alloy reveal that $d_{\mathrm{eff}}$ increases upon cooling but saturates near the first peak of the radial distribution function just before SE breakdown. This saturation defines a geometric upper bound for the collisional cross-section beyond which further slowdown is governed by cooperative, heterogeneous motion rather than local collisional transport. Our analysis yields a compact criterion for SE breakdown in a mean-field perspective and provides physically interpretable inputs for future data-driven models of glassy dynamics.

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Zhen-Wei Wu. 2025-12-04. A Kinetic Criterion for Stokes-Einstein Relation Breakdown Based on Effective Collisional Geometry. https://doi.org/10.1088/1674-1056%2Fae32ff

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