Diffusion-Coefficient Power Laws and Defect-Driven Glassy Dynamics in Swap Acceleration

Particle swaps can drastically accelerate dynamics in glass. The mechanism is expected to be vital for a fundamental understanding of glassy dynamics. To extract defining features, we propose a partial swap model with a fraction φs of swap-initiating particles, which can only swap locally with each other or with regular particles. We focus on the swap-dominating regime. At all temperatures studied, particle diffusion coefficients scale with φs in unexpected power laws with temperature-dependent exponents, consistent with the kinetic picture of glassy dynamics. At small φs, swap initiators, becoming defect particles, induce remarkably typical glassy dynamics of regular particles. This supports defect models of glass.