Abstract
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 (: diffusion constant; : mobility; ; Boltzmann’s constant; : 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, . Our finding implies that the characteristic time of this problem is not the structural relaxation time but the lifetime of dynamic heterogeneity, . A supercooled liquid can be regarded to be ergodic only over , which may be the slowest intrinsic time scale of the system.
- Received 9 May 2008
DOI:https://doi.org/10.1103/PhysRevLett.102.185701
©2009 American Physical Society