Banerjee Atreyee, Wales David J
Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom.
J Chem Phys. 2020 Sep 28;153(12):124501. doi: 10.1063/5.0015091.
A connection between the super-Arrhenius behavior of dynamical properties and the correlated dynamics for supercooled liquids is examined for a well known glass forming binary Lennard-Jones mixture and its repulsive counterpart, the Weeks-Chandler-Andersen potential, over a range of densities. When considering short time nonergodic trajectory segments of a longer ergodic trajectory, we observe that, independent of the potentials and densities, the apparent diffusivity follows Arrhenius behavior until low temperatures. Comparing the two potentials, where the ergodic diffusivities are known to be rather different, we find that the short-time nonergodic part is similar throughout the temperature range. By including a correlation factor in the nonergodic diffusivity, a rescaled value is calculated, which provides a reasonable estimate of the true ergodic diffusivity. The true diffusion coefficient and the correction factor collapse to a master plot for all densities at any given time interval. Hence, our results confirm a strong connection between fragility and dynamical correlation.
对于一种著名的玻璃形成二元 Lennard-Jones 混合物及其排斥对应物 Weeks-Chandler-Andersen 势，在一系列密度范围内，研究了动力学性质的超阿累尼乌斯行为与过冷液体的关联动力学之间的联系。当考虑较长遍历轨迹的短时间非遍历轨迹段时，我们观察到，与势和密度无关，表观扩散率在低温之前遵循阿累尼乌斯行为。比较两种势，已知其遍历扩散率有很大差异，我们发现短时间非遍历部分在整个温度范围内是相似的。通过在非遍历扩散率中包含一个相关因子，计算出一个重新标度的值，它能合理估计真实的遍历扩散率。在任何给定的时间间隔内，所有密度下的真实扩散系数和校正因子都汇聚到一个主图上。因此，我们的结果证实了脆性与动力学关联之间的紧密联系。
