H. H. Wills Physics Laboratory, Tyndall Avenue, Bristol, United Kingdom.
J Chem Phys. 2017 Aug 7;147(5):054501. doi: 10.1063/1.4994836.
Ageing phenomena are investigated from a structural perspective in two binary Lennard-Jones glassformers, the Kob-Andersen and Wahnström mixtures. In both, the geometric motif assumed by the glassformer upon supercooling, the locally favoured structure (LFS), has been established. The Kob-Andersen mixture forms bicapped square antiprisms; the Wahnström model forms icosahedra. Upon ageing, we find that the structural relaxation time has a time-dependence consistent with a power law. However, the LFS population and potential energy increase and decrease, respectively, in a logarithmic fashion. Remarkably, over the time scales investigated, which correspond to a factor of 10 change in relaxation times, the rate at which these quantities age appears almost independent of temperature. Only at temperatures far below the Vogel-Fulcher-Tamman temperature do the ageing dynamics slow.
从结构的角度研究了两种二元 Lennard-Jones 玻璃形成体——Kob-Andersen 和 Wahnström 混合物中的老化现象。在这两种混合物中，玻璃形成体在过冷时所具有的几何基元，即局部优势结构（LFS），已经确定。Kob-Andersen 混合物形成双帽正方形反棱柱体；Wahnström 模型形成二十面体。在老化过程中，我们发现结构弛豫时间具有幂律依赖性。然而，LFS 群体和势能分别以对数方式增加和减少。值得注意的是，在所研究的时间尺度内，这两个量的老化速率几乎与温度无关。只有在远低于 Vogel-Fulcher-Tamman 温度的温度下，老化动力学才会变慢。
