Two-order-parameter model of the liquid–glass transition. III. Universal patterns of relaxations in glass-forming liquids
Two-order-parameter model of the liquid–glass transition. III. Universal patterns of relaxations in glass-forming liquids
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DOI：
10.1016/j.jnoncrysol.2005.09.010
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发表时间：
2005-11
影响因子：
3.5
通讯作者：
Hajime Tanaka
中科院分区：
文献类型：
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作者：
Hajime Tanaka
在前面的两篇论文(论文I和II)中，我们根据液体的二阶参数模型，提出了与液体-玻璃转变有关的慢动力学的一个可能的起源。我们的模型表明，存在两个层次的动态结构非均质性，即“局部有利构造及其团簇”和“亚稳类固体岛屿”。在这张图的基础上，我们考虑了如何在同一模型中解释与玻璃跃迁有关的所有动力学模，从玻色子峰值到结构弛豫(α)模。我们将玻色子峰值指定为局域有利结构及其团簇的(准)局域振动模式，并将超快模式指定为它们的过阻尼态。我们将快β模指定为受限的“平移”运动，而慢β模指定为亚稳态岛中分子的受限的“转动”(激振)运动特性，该特性仅存在于TM∗以下。α模式与TM∗以下亚稳态岛屿的产生和湮灭动力学有关。讨论了模式的出现和消失随温度的变化，重点讨论了局部有利结构和亚稳类固体岛的行为。
In the preceding companion papers (paper I and II), we propose a possible origin of the slow dynamics associated with the liquid–glass transition in the light of our two-order-parameter model of liquids. Our model suggests that there exist two levels of dynamic structural heterogeneity, namely, ‘locally favored structures and their clusters’ and ‘metastable solid-like islands’. On the basis of this picture, we consider how all the dynamic modes associated with a glass transition, covering from the boson peak to the structural relaxation (α) mode, can be explained within the same model. We assign the boson peak to (quasi-) localized vibrational modes characteristic of locally favored structures and their clusters and the ultrafast mode to their overdamped states. We assign the fast β mode to the restricted ‘translational’ motion, while the slow β mode to the restricted ‘rotational’ (librational) motion characteristic of molecules in metastable islands, which exist only below Tm∗. The α mode is associated with dynamics of creation and annihilation of metastable islands below Tm∗. The appearance and disappearance of the modes as a function of the temperature are discussed, focusing on the behavior of locally favored structures and metastable solid-like islands.