Apparent Violation of the Fluctuation-Dissipation Theorem due to Dynamic Heterogeneity in a Model Glass-Forming Liquid
Apparent Violation of the Fluctuation-Dissipation Theorem due to Dynamic Heterogeneity in a Model Glass-Forming Liquid
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DOI：
10.1103/physrevlett.102.185701
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发表时间：
2009-05-08
影响因子：
8.6
通讯作者：
Tanaka, Hajime
中科院分区：
文献类型：
--
作者：
Kawasaki, Takeshi;Tanaka, Hajime
本文利用数值模拟方法研究了过冷二维多分散胶体液体中迁移率与平移扩散之间的关系。我们发现一个明显的违反爱因斯坦-Smoluchowski（ES）关系D=k（B）T μ（D：扩散常数; μ：迁移率; k（B）;玻尔兹曼常数; T：温度）。这种破坏是由于粒子的屈服应力使被驱动粒子难以进入高阶阻塞区的直接结果。这种明显的ES违反的程度仅由缓慢堵塞区域的特征尺寸xi控制。我们的发现意味着这个问题的特征时间不是结构弛豫时间τ（α），而是动态异质性的寿命τ（xi）。一个过冷的液体可以被认为是遍历只有超过τ（xi），这可能是最慢的系统的内在时间尺度。
Here we study the relation between the mobility and the translational diffusion in supercooled two-dimensional polydisperse colloidal liquids, using numerical simulations. We find an apparent violation of the Einstein-Smoluchowski (ES) relation D=k(B)T mu (D: diffusion constant; mu: mobility; k(B); Boltzmann's constant; T: temperature). The violation is a direct consequence of the fact that it is difficult for a driven particle to enter a jammed region with high order due to its yield stress. The degree of this apparent ES violation is controlled solely by the characteristic size of slow jammed regions, xi. Our finding implies that the characteristic time of this problem is not the structural relaxation time tau(alpha) but the lifetime of dynamic heterogeneity, tau(xi). A supercooled liquid can be regarded to be ergodic only over tau(xi), which may be the slowest intrinsic time scale of the system.