在超冷液体中出现的促进和玻璃动态
Muhammad R Hasyim1, Kranthi K Mandadapu1,2
1Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA 94720.
概括
这项研究揭示了局部债券交换事件或激发如何推动超冷液体中的动态促进. 这些激发之间的弹性相互作用解释了复杂的玻璃式放松动态和超-阿雷尼乌斯温度依赖.
科学领域:
- 凝聚物质物理学 凝聚物质物理学
- 材料科学 材料科学 材料科学
- 统计力学 统计力学
背景情况:
- 超冷液体表现出复杂的动态,包括空间异质运动和超阿雷尼乌斯放松,这些现象归因于动态促进.
- 动态促进,即局部运动触发进一步的运动,对于理解玻璃式放松至关重要,但缺乏明确的理论起源.
- 现有的模型很难解释驱动缓解的微观机制及其对放松时间尺度的影响.
研究的目的:
- 开发一个理论框架,解释超冷液体中动态促进的微观起源.
- 阐明局部事件及其相互作用如何支配玻璃动态的新兴特性.
- 为了将理论预测与超冷液态行为的实验和模拟观测联系起来.
主要方法:
- 基于局部化的债券交换事件 (激发) 和它们的弹性相互作用,开发了一个理论.
- 利用线性弹性理论和马尔科夫过程来建模系统.
- 模拟了一个包含弹性应力和激发相互作用的模型.
主要成果:
- 该模型重现了玻璃动态的关键方面:伸展指数级放松,放松时间的超级Arrhenius缩放和2D有限尺寸效应.
- 在短期和中期时间尺度的平均平方位移 (MSD) 中预测的亚扩散行为.
- 衍生的声贡献,这些与激发贡献相结合,解释了两步放松和弹道-亚扩散-扩散MSD交叉.
结论:
- 该理论成功地解释了来自局部债券交换事件和弹性相互作用的动态促进的出现.
- 该模型为理解超冷液体中的各种现象提供了一个统一的框架,从放松动态到MSD行为.
- 这项工作为动态促进提供了微观基础,促进了对玻璃状态的理解.
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