Dynamic arrest in model porous media -- intermediate scattering functions

TL;DR

This study uses molecular dynamics simulations to analyze how tracer particles move in disordered porous media near the localization transition, revealing anomalous transport and dynamic scaling behaviors.

Contribution

It provides new insights into the spatio-temporal dynamics and intermediate scattering functions of particles in porous media near the localization transition, combining simulations with mode-coupling theory.

Findings

Transport becomes anomalous and non-Gaussian near the transition.

Intermediate scattering functions reveal self-similar spatial structures.

Mode-coupling approach predicts certain aspects of the dynamics accurately.

Abstract

Heterogeneous media constitute random disordered environments where transport is drastically hindered. Employing extensive molecular dynamics simulations, we investigate the spatio-temporal dynamics of tracer particles in the Lorentz model in the vicinity of the localization transition. There transport becomes anomalous and non-gaussian due to the presence of self-similar spatial structures, and dynamic scaling behavior is anticipated. The interplay of different time and length scales is revealed by the intermediate scattering functions, which are sensitive both to the underlying spatial fractal as well as the anomalous transport. We compare our numerical results in the transition regime to a mode-coupling approach, and find that certain aspects are surprisingly well predicted.