Statistical Mechanics of the Dynamics in Quiescent and Driven Glassy Fluids

科罗拉多州立大学的Grzegorz Szamel得到了化学系化学理论、模型和计算方法计划的支持，该计划研究静止和驱动的玻璃流体中分子的动力学。早期的研究表明，在接近玻璃化转变时，动力学不仅变得更慢，而且越来越不均匀。最近的实验表明，分子间相互作用的性质决定了分子间的动态非均质性。目前的工作采用计算和理论相结合的方法来分析具有排斥和吸引相互作用的流体中的动态非均质性。此外，Szamel和他的同事致力于阐明动态异质性和慢动态之间的联系。在被驱动的玻璃流体领域，最初的目标是研究由流动引起的长程关联。长期目标是开发一种适用于热系统和非热系统的驱动胶体玻璃流体动力学的理论。当足够快的过冷或致密化时，各种流体经历向无定形固体状态的转变。这种转变通常被称为玻璃转变。在此过程中获得的材料，特别是聚合物和金属玻璃，有许多实际应用。然而，玻璃过渡的本质仍然存在激烈的争论。众所周知，在接近玻璃化转变时，流体的动力学以一种令人惊讶的不均匀的方式减慢。然而，这种所谓的动态异质性的作用尚不清楚。Szamel教授和他的团队描述了玻璃流体的非均匀动力学，并研究了它与玻璃化转变的关系。复杂材料通常通过施加非均匀流来探测或排序。特别是，众所周知，剪切流可以熔化由胶体颗粒制成的玻璃。Szamel教授的研究将描述这一过程，并将静止和流动的玻璃胶体悬浮液的行为联系起来。

Grzegorz Szamel of Colorado State University is supported by an award from the Chemical Theory, Models and Computational Methods program in the Chemistry division to investigate the dynamics of molecules in quiescent and driven glassy fluids. Earlier studies showed that, upon approaching the glass transition, the dynamics become not only slower but also increasingly heterogeneous. Recent experiments suggested that the dynamic heterogeneity depends on the character of intermolecular interactions. The current work employs both computational and theoretical methods to analyze the dynamic heterogeneity in fluids with repulsive and attractive interactions. In addition, Szamel and his coworkers work to elucidate the connection between dynamic heterogeneity and slow dynamics. In the area of driven glassy fluids, the initial goal is to investigate long range correlations induced by the flow. The long term goal is to develop a theory for the dynamics in driven colloidal glassy fluids applicable to both thermal and athermal systems.Upon sufficiently fast supercooling or densification, a great variety of fluids undergo a transformation to an amorphous solid state. This transformation is commonly referred to as the glass transition. Materials obtained in this process, especially polymeric and metallic glasses, have many practical applications. However, the very nature of the glass transition is still hotly debated. It is known that upon approaching the glass transition, the dynamics of the fluid slows down in a surprisingly non-uniform way. The role of this so-called dynamic heterogeneity, however, is not understood. Professor Szamel and his group characterize the non-uniform dynamics of glassy fluids and investigate its relation to the glass transition. Complex materials are often probed or ordered by imposing non-uniform flow. In particular, shear flow is known to melt glasses made of colloidal particles. Professor Szamel's research will characterize this process and relate the behavior of quiescent and flowing glassy colloidal suspensions.