An alternative approach to study the heterogeneous dynamics and its consequent dynamic correlation length that emerges in a glass-former

CRISTIAN BALBUENA

Workshop; 3rd Workshop on Structure and Dynamics of Glassy, Supercooled and Nanoconfined Fluids; 2019

Inthis work, the relaxation of a simple bead-spring polymer system wasinvestigated with Molecular Dynamic simulations near its glasstransition temperature. We developed a new way to look at the dynamiclength scale in this glass-former, focusing on the correlated motionof particles in an isoconfigurational ensemble (ICE). We found that,while the usual dynamic four-point correlation length deviates fromthe structural length scale (calculated with the point-to-set method)at low temperatures, Pearson's length behaves similar to the staticlength in the whole temperature range [1]. Moreover, similar to whathappens with mobility, monomers with higher correlation areclustered, and the clustering increases with decreasing temperature.An interesting result is that regions with high Pearson dynamiccorrelation are not coincident with highly mobile or immobileregions. This results represents a new approach to the study ofdynamic heterogeneity that emerges in glass forming liquids,complementing the more traditional characterization in terms ofmobility [2]. Additionally we studied the breakdown of theStokes-Einstein Relation (SER) in connection with dynamicsusceptibility calculated for an ICE, such that the effect of thestructure on dynamics can be discriminated. We found that the onsetof structure effects on the dynamical behavior is coincident with theonset of SER breakdown [3].p { margin-bottom: 0.25cm; line-height: 115%; }