Condensed Matter Seminars

How do glassy materials begin to flow? Experiments and simulations have confirmed that flow occurs via localized rearrangements in most jammed solids at finite temperatures and strain rates, but in the past it has been difficult to identify structural defects, or soft spots, based on the underlying structure of the packing alone. We have developed a method to systematically identify a population of soft spots by analyzing the low-energy vibrational modes of a soft-sphere packing. We show that the soft spots are structurally distinct from the remainder of the packing and that under quasi-static shear a soft spot from the population will accommodate deformation. Finally, we discuss how statistics of these soft spot populations could be used to test predictions of theoretical models for plastic flow.