| Abstract
| - Using molecular dynamics simulations, we have determined that the nature of dynamical heterogeneity injammed liquids is very sensitive to short-ranged attractions. Weakly attractive systems differ little from densehard-sphere and Lennard-Jones fluids. Particle motion is punctuated and tends to proceed in steps of roughlya single particle diameter. Both of these basic features change in the presence of appreciable short-rangedattractions. Transient periods of particle mobility and immobility cannot be discerned at intermediate attractionstrength, for which structural relaxation is greatly enhanced. Strong attractions, known to dramatically inhibitrelaxation, restore bimodality of particle motion. But in this regime, transiently mobile particles move insteps that are significantly more biased toward large displacements than those in the case of weak attractions.This modified feature of dynamical heterogeneity, which cannot be captured by conventional mode couplingtheory, verifies recent predictions from a model of spatially correlated facilitating defects.
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