CONICET | Buscador de Institutos y Recursos Humanos

In this work we review and expand some recent advances in the relaxation of supercooled glassy liquids by means of molecular dynamics simulations. In particular, we make emphasis on the recent finding that these systems accomplish the structural relaxation by means of relatively compact clusters of dynamically correlated particles, the d-clusters, which act as cooperatively relaxing units in the spirit of the Adam and Gibbs picture. These studies have determined the fact that the behavior of such systems at such low temperatures consists in the exploration of a finite region of configuration space enclosing several distinct local minima, named metabasin, followed by a sharp crossing to a different metabasin. The characteristic time between metabasin transitions is commensurate with the structural relaxation time, thus indicating that these transitions are relevant for the longtime dynamics. Additionally, these temporarily "hot regions" have been shown to be related to structurally unjammed regions of the sample, thus making evident the relationship between structure and dynamics. The generality of this scenario has been suggested, since it has been shown to hold valid for very different glassy systems including model glassformers, polymers and supercooled water, and has recently received some experimental support by means of a single-molecule approach. However, technical requirements have restricted these studies to small systems. Thus, the aim of the present work is to extend these results to large systems in order to complete such a picture. Additionally, the simultaneous study of different subsystems within a large one will enable us to detect certain space-time correlations between different d-clusters, together with the determination of the time evolution of jamming regions along the system, thus elucidating the interplay between structure and dynamics.

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