Staley Hannah, Flenner Elijah, Szamel Grzegorz
Department of Physics, Colorado State University, Fort Collins, Colorado 80523, USA.
Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA.
J Chem Phys. 2015 Dec 28;143(24):244501. doi: 10.1063/1.4938082.
We examined dynamic heterogeneity in a model tetrahedral network glass-forming liquid. We used four-point correlation functions to extract dynamic correlation lengths ξ4(a)(t) and susceptibilities χ4(a)(t) corresponding to structural relaxation on two length scales a. One length scale corresponds to structural relaxation at nearest neighbor distances and the other corresponds to relaxation of the tetrahedral structure. We find that the dynamic correlation length ξ4(a) grows much slower with increasing relaxation time than for model fragile glass formers. We also find that χ4(a)∼(ξ4(a))(z) for a range of temperatures, but z < 3 at the lowest temperatures examined in this study. However, we do find evidence that the temperature where Stokes-Einstein violation begins marks a temperature where there is a change in the character of dynamically heterogeneous regions. Throughout the paper, we contrast the structure and dynamics of a strong glass former with that of a representative fragile glass former.
我们研究了一个模型四面体网络玻璃形成液体中的动态非均匀性。我们使用四点关联函数来提取对应于两个长度尺度a上结构弛豫的动态关联长度ξ4(a)(t)和磁化率χ4(a)(t)。一个长度尺度对应于最近邻距离处的结构弛豫，另一个对应于四面体结构的弛豫。我们发现，与模型易碎玻璃形成体相比，动态关联长度ξ4(a)随弛豫时间增加的增长要慢得多。我们还发现在一系列温度下χ4(a)∼(ξ4(a))(z)，但在本研究中所考察的最低温度下z < 3。然而，我们确实发现有证据表明，斯托克斯 - 爱因斯坦关系违背开始出现的温度标志着动态非均匀区域特征发生变化的温度。在整篇论文中，我们将一种强玻璃形成体的结构和动力学与一种代表性易碎玻璃形成体的结构和动力学进行了对比。
