介观弹性是否控制玻璃形成液体中的黏性减慢？
Does mesoscopic elasticity control viscous slowing down in glassforming liquids?
AI总结：
本文提出以固有态局部偶极响应定义的介观刚度κ(T)解释玻璃形成液体的黏性减慢，并通过计算机液体检验其与活化能垒的关系及势能面差异。
摘要：
液体在接近玻璃化转变时弛豫动力学的显著减慢仍是一个备受争议的问题，其核心谜题在于活化能垒ΔE(T)随温度T降低而出现的难以捉摸的增长。一类被称为弹性模型的理论框架将这种温度依赖性归因于液体宏观弹性的变化，并以高频剪切模量G_∞(T)来量化。尽管弹性模型在若干实验研究中获得了一定支持，但这些模型没有考虑与过冷液体中结构弛豫相关的空间结构、长度尺度和非均质性。在此，我们提出黏性减慢由一种介观弹性刚度κ(T)控制，其定义为液体底层固有态中响应场对局部偶极力的特征刚度。首先，我们表明，在若干计算机液体中，κ(T)——它与表征玻璃中准局域化、非声子激发的能量和长度尺度密切相关——随T降低而增强的程度，要大于宏观固有态剪切模量G(T)。其次，我们表明，简单关系ΔE(T)∝κ(T)对某些计算机液体显著成立，这意味着液体底层介观弹性与焓性能垒之间存在直接联系。另一方面，我们表明，对于其他计算机液体，上述关系并不成立。最后，我们提供有力证据表明，使ΔE(T)∝κ(T)关系成立的计算机液体与该关系不成立的计算机液体相区别的是，后者具有高度颗粒化的势能面，其中存在许多由低活化能垒分隔的子盆地。【摘要其余部分从略】
英文摘要：
The dramatic slowing down of relaxation dynamics of liquids approaching the glass transition remains a highly debated problem, where the crux of the puzzle resides in the elusive increase of the activation barrier $ΔE(T)$ with decreasing temperature $T$. A class of theoretical frameworks -- known as elastic models -- attribute this temperature dependence to the variations of the liquid's macroscopic elasticity, quantified by the high-frequency shear modulus $G_\infty(T)$. While elastic models find some support in a number of experimental studies, these models do not take into account the spatial structures, length scales, and heterogeneity associated with structural relaxation in supercooled liquids. Here, we propose that viscous slowing down is controlled by a mesoscopic elastic stiffness $κ(T)$, defined as the characteristic stiffness of response fields to local dipole forces in the liquid's underlying inherent states. First, we show that $κ(T)$ -- which is intimately related to the energy and length scales characterizing quasilocalized, nonphononic excitations in glasses -- increases more strongly with decreasing $T$ than the macroscopic inherent state shear modulus $G(T)$ in several computer liquids. Second, we show that the simple relation $ΔE(T)\proptoκ(T)$ holds remarkably well for some computer liquids, implying a direct connection between the liquid's underlying mesoscopic elasticity and enthalpic energy barriers. On the other hand, we show that for other computer liquids, the above relation fails. Finally, we provide strong evidence that what distinguishes computer liquids in which the $ΔE(T) \propto κ(T)$ relation holds, from those in which it does not, is that the latter feature highly granular potential energy landscapes, where many sub-basins separated by low activation barriers exist. [Rest of abstract abridged]
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
