Dynamical equivalence for the caging-release colloidal problem
Phys. Rev. E 114, 044119 – Published 13 October, 2026
DOI: https://doi.org/10.1103/5wb4-6pvf
Abstract
Brownian particles in complex media often exhibit diffusion-caging-diffusion dynamics: short-time diffusion, an intermediate plateau due to diffusion hindrance, and long-time diffusion, usually attributed to cage-release events. We analyze an alternative mechanism that reproduces the same phenomenology: a perfectly confining cage undergoing stochastic motion that transports the particle without allowing escape. Despite their distinct physical origins, both mechanisms yield identical MSD behavior with the canonical three-regime structure. In contrast, the non-Gaussian parameter (NGP) provides a clear discriminator between them. For the two models presented, we provide analytical results for the NGP that conceptually support the main findings obtained from the simulation. These results offer diagnostic tools for microrheology and refine the interpretation of dynamical signatures near the glass transition.
