Schwartzman-Nowik Zohar, Lerner Edan, Bouchbinder Eran
Chemical and Biological Physics Department, Weizmann Institute of Science, Rehovot 7610001, Israel.
Institute for Theoretical Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands.
Phys Rev E. 2019 Jun;99(6-1):060601. doi: 10.1103/PhysRevE.99.060601.
There is growing evidence that relaxation in glassy materials, both spontaneous and externally driven, is mediated by localized soft spots. Recent progress made it possible to identify the soft spots inside glassy structures and to quantify their degree of softness. These softness measures, however, are typically scalars, not taking into account the tensorial, anisotropic nature of soft spots, which implies orientation-dependent coupling to external deformation. Here, we derive from first principles the linear response coupling between the local heat capacity of glasses, previously shown to provide a measure of glassy softness, and external deformation in different directions. We first show that this linear response quantity follows an anomalous, fat-tailed distribution related to the universal ω^{4} density of states of quasilocalized, nonphononic excitations in glasses. We then construct a structural predictor as the product of the local heat capacity and its linear response to external deformation, and show that it offers an enhanced predictability of plastic rearrangements under deformation in different directions, compared to the purely scalar predictor.
越来越多的证据表明，玻璃态材料中的弛豫，无论是自发的还是外部驱动的，都是由局部软点介导的。最近的进展使得识别玻璃态结构内部的软点并量化其柔软程度成为可能。然而，这些柔软度测量通常是标量，没有考虑到软点的张量、各向异性性质，这意味着与外部变形的耦合依赖于方向。在这里，我们从第一原理推导出玻璃局部热容量（先前已证明其可作为玻璃态柔软度的一种度量）与不同方向外部变形之间的线性响应耦合。我们首先表明，这种线性响应量遵循一种与玻璃中准局域化、非声子激发的通用ω⁴态密度相关的异常肥尾分布。然后，我们构建了一个结构预测器，它是局部热容量与其对外部变形的线性响应的乘积，并表明与纯标量预测器相比，它在不同方向变形下对塑性重排具有更高的预测能力。
