Space-resolved dynamics of a tracer in a disordered solid

TL;DR

This study investigates the slow, complex motion of a tracer particle in a disordered solid near the glass transition, using simulations and scaling theory to understand subdiffusive behavior.

Contribution

It provides a detailed analysis of tracer dynamics in a disordered solid near criticality, combining molecular dynamics simulations with critical phenomena theory.

Findings

Identification of subdiffusive motion near the critical point

Characterization of transport via correlation functions and diffusion coefficients

Validation of dynamic scaling theory against simulation data

Abstract

The dynamics of a tracer particle in a glassy matrix of obstacles displays slow complex transport as the free volume approaches a critical value and the void space falls apart. We investigate the emerging subdiffusive motion of the test particle by extensive molecular dynamics simulations and characterize the spatio-temporal transport in terms of two-time correlation functions, including the time-dependent diffusion coefficient as well as the wavenumber-dependent intermediate scattering function. We rationalize our findings within the framework of critical phenomena and compare our data to a dynamic scaling theory.