Connections between structural jamming, local metabasin features, and relaxation dynamics in a supercooled glassy liquid

Abstract

Dynamics in glass-forming liquids in the supercooled regime vary considerably from one point of the sample to another suggesting the existence of regions with different degrees of jamming. In fact, the existence of relatively compact regions with particles with an enhanced propensity for motion has been detected in model glassy systems. In turn, the structural relaxation has been shown to be accomplished by means of a series of fast transitions between metabasins in the potential energy landscape involving the collective motion of a substantial number of particles arranged in relatively compact clusters (democratic clusters or d clusters). In this work we shall complete this picture by identifying the connections between local structural jamming, metabasin confining strength, and d clusters. Thus we shall demonstrate that the degree of jamming of the local structure dictates the confining strength of the local metabasin and that the local high propensity regions and the d clusters are not only similar in nature but that they share a significant amount of particles.

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

“…The presence of relatively compact regions with high propensity for motion indicates domains made up of particles with high tendency to be mobile wherein the events responsible for the α relaxation occur 23,24,29 . The fact that the spatial distribution of the very short time propensity 21,29 is sufficient to signal such regions and that some of such high propensity particles will take part of a d-cluster in the different IC trajectories at a later time 24,29 would mean that these particles are not at ease (not blocked) in the local structure and try for some time without success to relax their condition until eventually, a collective motion of many of them is able to perform a large scale relaxation event. While a rigorous complete comparison is not possible at this stage, this behavior seems to be in accord with an appealing very recently proposed soft mode explanation of glassy dynamics 31 .…”

“…Within such timescales, the system changes many times the inherent structure (IS, local minimum or basin of attraction in the potential energy surface), an event that entails a small localized particle rearrangement, but has not been able to perform a collective long-range rearrangement characteristic of a d-cluster since it has been confined within the local metabasin, a collection of structurally very similar configurations. The d-cluster, which brings the system out of such MB, occurs within the high propensity region 24,29 and has been related to the soft modes present in the system at such times 19,32,33 . To summarize, in this work we have shown that not only the local structure poses its constraints on the dynamics of glassy systems, but that the opposite is also valid, that is, the dynamical events responsible for the α relaxation clearly modify the propensity pattern.…”

“…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 .…”

Spatial arrangements of particles with different mobility tendencies in a model glass-former

“…A recent breakthrough has been provided by the definition of the propensity notion [21,22]. By means of the isoconfigurational ensemble (IC, the generation of multiple trajectories from the same configuration, that is, particle positions, but with particle velocities chosen at random from the appropriate Boltzmann distribution) 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 a higher propensity are not homogeneously distributed within the sample but arranged in relatively compact clusters [21][22][23][24]. The time extent of such influence of the local structure on the dynamics has been shown to be on the order of the MB residence time, a timescale shorter than the structural or α-relaxation time (τ α ) [23].…”

Dynamics, thermodynamics properties and potential energy landscape of germanium dioxide

“…Several MD simulations have provided evidence of the relationship between the dynamics of supercooled liquid and the PEL. The dynamics description of the liquid was performed in term of the distance matrix (DM) [15][16][17].…”