Structural Soft Spots Control Flow in Ordered and Disordered Solids
Prof. Mary E. "Lisa" Manning , Physics Dept., Syracuse University
| When: | Feb 02, 2012 | 1:00 pm - 2:00 pm |
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| Where: | McKay Lab, Room 402 |
Abstract: Both solids and fluids can flow under applied stress. In crystalline solids, flow occurs via particle rearrangements controlled by a population of dislocations, while in fluids, particle rearrangements occur everywhere throughout the material. In disordered solids, flow generally occurs via localized rearrangements, but it has remained unclear whether a solid-like or fluid-like description is more appropriate for describing flow in such systems. By analyzing simulations of an athermal model glass, we have determined a length scale and an energy scale that characterizes structural "soft spots'' in the vibrational modes in these systems. We identify a robust, long-lived population of such spots, and show that particle rearrangements are initiated there. We find that the spots are structurally different from the remainder of the packing, and that the density of spots decreases with increasing packing fraction. We show that these spots can be identified in an experimental colloidal glass at finite temperatures and in simulations of crystals with defects. Taken together, these results support a solid-like description of flow controlled by a population of localized flow defects in glassy materials.
| Host: | Frans Spaepen |
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| Contact: |
Barbara Sewall
sewall@seas.harvard.edu |
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