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arXiv 1508.04516cond-mat.soft
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应用于密度反常液体的玻璃化转变的弹性模型

Elastic models of the glass transition applied to a liquid with density anomalies

M. Pica Ciamarra, Peter Sollich

摘要:

玻璃化转变的弹性模型将结构玻璃的弛豫动力学和弹性性质联系起来。它们是基于这样的假设,即松弛动力学是通过能量景观中的激活事件发生的,能量景观的能量尺度由材料的弹性决定。在这里,我们调查是否这样的弹性模型描述通过一个纯粹的排斥谐波势相互作用的粒子系统的弛豫动力学,专注于体积分数和温度范围,其特征在于由熵驱动的水-类似密度异常。我们发现明确的弛豫时间和扩散率之间的相关性,一方面,和平台剪切模量和德拜-沃勒因子的其他,从而支持弹性模型的玻璃化转变的有效性。然而,我们也表明,高原剪切模量是不相关的系统的基本能量景观的功能,在最近的结果与幂律势的差异。这对弹性模型的常见势能景观解释提出了挑战。

英文摘要:

Elastic models of the glass transition relate the relaxation dynamics and the elastic properties of structural glasses. They are based on the assumption that the relaxation dynamics occurs through activated events in the energy landscape whose energy scale is set by the elasticity of the material. Here we investigate whether such elastic models describe the relaxation dynamics of systems of particles interacting via a purely repulsive harmonic potential, focusing on a volume fraction and temperature range that is characterized by entropy--driven water--like density anomalies. We do find clear correlations between relaxation time and diffusivity on the one hand, and plateau shear modulus and Debye--Waller factor on the other, thus supporting the validity of elastic models of the glass transition. However, we also show that the plateau shear modulus is not related to the features of the underlying energy landscape of the system, at variance with recent results for power--law potentials. This challenges the common potential energy landscape interpretation of elastic models.

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