Reproducibility of Dynamical Heterogeneities and Metabasin Dynamics in Glass Forming Liquids: The Influence of Structure on Dynamics

Abstract

The discovery that the propensity for particle motion in a supercooled liquid is completely determined by the initial structure pointed to the existence of a causal link between structure and dynamics in glassy systems. Here we demonstrate that this underlying influence of structure is only local in time, fading out beyond the metabasin lifetime much before the relaxation time. Thus, our results reveal the irreproducibility of metabasin dynamics and support the scenario of a random walk on metabasins for the long time diffusion.

Metabasin dynamics and local structure in supercooled water

“…An interesting finding in such direction for binary Lennard-Jones systems suggested a compelling picture for glassy dynamics [8]: the α-relaxation corresponds to a small number of fast crossings from one metabasin to a neighboring one involving the collective motion of a significant number of particles that form a relatively compact cluster, called "democratic cluster" or d-cluster. Since the influence of the structure on dynamics is only local in time [17], the long time dynamics could be described as a random walk on metabasins [14,17] triggered by d-clusters [17]. Thus, it would be of great interest to learn whether these results hold valid for other glassy systems beyond binary Lennard-Jones systems so as to determine the generality of such a scenario.…”

Diffusion in a Cu-Zr metallic glass studied by microsecond-scale molecular dynamics simulations

“…A close relationship between atomic mobility and the local structure has been demonstrated in supercooled liquids [5]. However, the underlying influence of structure on atomic mobility is shown only local in time, fading out much shorter than the α-relaxation time [6]. Therefore many studies have been carried out focusing on a long time correlation, such as the dynamical facilitation which denotes propagation of the mobile regions due to the mobility transfer of mobile particles [7].…”

Time evolution of dynamic propensity in a model glass former: The interplay between structure and dynamics

“…16,23 for details): We perform an MD simulation and record equally-spaced configurations (for example 101 configurations, as in Refs. 16,23) for an α-relaxation total run time (τ α = 4000, thus consecutively recorded configurations are separated in time by φ = 10 % t * = 40) and build the following distance matrix…”

“…By means of the isoconfigurational ensemble (IC) it has been determined that the propensity of the particles (their tendency to be mobile) is in fact determined by the initial configuration of the sample and that the particles with the higher propensity are not homogeneously distributed within the sample but arranged in relatively compact clusters 21,22 . The time extent of the influence of the local structure on the dynamics has also been shown to be on the order of the MB residence time, a timescale shorter than the α−relaxation time (τ α ) 23 . In a previous work, it has been shown for the binary Lennard-Jones system that the high propensity regions of a given initial configuration represent unblocked regions wherein d-clusters occur in the subsequent dynamics (for any given isoconfigurational realization or trajectory initiated in such configuration) 24 .…”