Cooperative molecular motion and spatially heterogeneous dynamics in supercooled liquids and glasses |
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Materials:
Nanomaterials
Metals
Semiconductors
Application: Nanotechnology Structural Technique: Computation |
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Over the past several years, we have performed extensive molecular dynamics simulation studies of the behavior of liquids cooled below their crystallization temperature to the supercooled liquid state. As these metastable liquids approach their glass transition temperature, the dynamics of the individual molecules comprising the liquid become increasingly spatially heterogeneous. Our group discovered in 1998 that this heterogeneity involves the cooperative motion of molecules into highly coordinated, one-dimensional string-like objects in which molecules follow one another like dancers in a conga line. These strings aggregate into clusters whose transient behavior appears to dominate much of the bulk dynamics of supercooled and glass-forming liquids. Through MD simulations and the development of a statistical mechanical description of correlated dynamics, we continue to study these remarkable features of the liquid state in order to ascertain how and why they form, and to unlock further secrets of the nature of the glass transition. |