Szamel Grzegorz, Flenner Elijah
Department of Chemistry, Colorado State University, Fort Collins, CO 80525, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2006 Jan;73(1 Pt 1):011504. doi: 10.1103/PhysRevE.73.011504. Epub 2006 Jan 19.
We propose a quantitative measure of a time scale on which Fickian diffusion sets in for supercooled liquids, and we use Brownian dynamics computer simulations to determine the temperature dependence of this onset time in a Lennard-Jones binary mixture. The time for the onset of Fickian diffusion ranges between 6.5 and 31 times the relaxation time (the relaxation time is the characteristic relaxation time of the incoherent intermediate scattering function). The onset time increases faster with decreasing temperature than the relaxation time. Mean-squared displacement at the onset time increases with decreasing temperature.
我们提出了一种时间尺度的定量测量方法，在该时间尺度上，过冷液体开始出现菲克扩散，并且我们使用布朗动力学计算机模拟来确定在 Lennard-Jones 二元混合物中该起始时间的温度依赖性。菲克扩散开始的时间范围在弛豫时间的 6.5 至 31 倍之间（弛豫时间是非相干中间散射函数的特征弛豫时间）。起始时间随温度降低的增加速度比弛豫时间更快。起始时间的均方位移随温度降低而增加。
