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

BALBUENA, CRISTIAN; SOULÉ, EZEQUIEL R.; GIANETTI, MELISA M.

Ciudad Autónoma de Buenos Aires

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

CNEA-ANPCYT

In this work, the relaxation of a simple bead-spring polymer system was investigated with MolecularDynamic simulations near its glass transition temperature. We developed a new way to look at thedynamic length scale in this glass-former, focusing on the correlated motion of particles in anisoconfigurational ensemble (ICE). We found that, while the usual dynamic four-point correlationlength deviates from the structural length scale (calculated with the point-to-set method) at lowtemperatures, Pearson´s length behaves similar to the static length in the whole temperature range[1]. Moreover, similar to what happens with mobility, monomers with higher correlation areclustered, and the clustering increases with decreasing temperature. An interesting result is thatregions with high Pearson dynamic correlation are not coincident with highly mobile or immobileregions. This results represents a new approach to the study of dynamic heterogeneity that emergesin glass forming liquids, complementing the more traditional characterization in terms of mobility[2]. Additionally we studied the breakdown of the Stokes-Einstein Relation (SER) in connection withdynamic susceptibility calculated for an ICE, such that the effect of the structure on dynamics can bediscriminated. We found that the onset of structure effects on the dynamical behavior is coincidentwith the onset of SER breakdown [3].References:[1] C. Balbuena, M. M. Gianetti, and E. R. Soulé, J. Chem. Phys., 150, 234508 (2019).[2] C. Balbuena, M. M. Gianetti, and E. R. Soulé, J. Chem. Phys., 149, 094506 (2018).[3] C. Balbuena and E. R. Soulé, J. Phys.: Condens. Matter, submitted.