Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research, 21 Brundavan Colony, Narsingi, Hyderabad 500075, India.
Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India.
Phys Rev Lett. 2016 Feb 26;116(8):085701. doi: 10.1103/PhysRevLett.116.085701.
Temporal relaxation of density fluctuations in supercooled liquids near the glass transition occurs in multiple steps. Using molecular dynamics simulations for three model glass-forming liquids, we show that the short-time β relaxation is cooperative in nature. Using finite-size scaling analysis, we extract a growing length scale associated with beta relaxation from the observed dependence of the beta relaxation time on the system size. We find, in qualitative agreement with the prediction of the inhomogeneous mode coupling theory, that the temperature dependence of this length scale is the same as that of the length scale that describes the spatial heterogeneity of local dynamics in the long-time α-relaxation regime.
在玻璃化转变附近的过冷液体中，密度涨落的弛豫过程是分多步进行的。我们通过对三种模型玻璃形成液体的分子动力学模拟，表明短时间β弛豫在本质上是协同的。通过有限尺寸标度分析，我们从观察到的β弛豫时间对系统尺寸的依赖关系中，提取出与β弛豫相关的增长长度尺度。我们发现，与非均匀模式耦合理论的预测定性一致，这个长度尺度的温度依赖性与描述长时α弛豫区局部动力学空间非均匀性的长度尺度相同。
