Multi-time correlation analysis for heterogeneous dynamics in glass-forming liquids

介绍了一个多时间扩展的密度相关函数，揭示了在玻璃形成液体的动力学不均匀性的时间信息。在这项研究中使用的多时间相关函数是类似于在多维非线性光谱分析的高阶响应函数。我们确认，二维表示是敏感的动力学的异质性，这些揭示了相关的运动，存在于广泛的时间尺度的耦合。从这个分析中，我们评估的动力学异质性的寿命和它的温度依赖性系统。此外，我们研究的物理作用的动力学不均匀性的生命周期的粘度和自扩散常数之间的斯托克斯-爱因斯坦（SE）关系的违反。SE关系的大违反的特点是时间尺度长于在高度过冷液体的动力学不均匀性的寿命。

A multi-time extension of a density correlation function is introduced to reveal temporal information about dynamical heterogeneity in glass-forming liquids. A multi-time correlation function utilized in this study is analogous to the higher-order response function analyzed in multidimensional nonlinear spectroscopy. We confirm that the two-dimensional representations are sensitive to the dynamical heterogeneity and that these reveal the couplings of correlated motions, which exist over a wide range of time scales. From this analysis, we evaluated the lifetime of the dynamical heterogeneity and its temperature dependence systematically. Furthermore, we examine the physical role of the lifetime of dynamical heterogeneity in the violation of the Stokes-Einstein (SE) relation between viscosity and self-diffusion constant. Large violations of the SE relation are characterized by time scales longer than the lifetime of the dynamical heterogeneity in highly supercooled liquids.