论文标题
将放松时间连接到动态长度尺度
Connecting Relaxation Time to a Dynamical Length Scale in Athermal Active Glass Formers
论文作者
论文摘要
超冷的液体显示空间本质上异质的动力学。这本质上意味着，在熔点以下的温度下，液体某些区域的颗粒动力学可以比其他区域快。这种行为通常被称为动态异质性，使参与玻璃过渡研究的研究人员着迷了二十年。在所有玻璃过渡研究中，从根本上重要的问题是，是否可以将不断增长的放松时间与同时增长的长度量表联系起来。在本文中，我们超越了普通玻璃形成液体的领域，并研究了在自我推进的“活跃”玻璃中增长的动态长度比例$ξ$的起源。使用结构相关构建的长度尺度与随着液体变成空间异质性而形成的慢移动粒子簇的平均大小非常吻合。 We further report that the concomitantly growing $α$- relaxation time exhibits a simple scaling law, $τ_α\sim \text{exp} (ξμ/ T_{eff})$, with $μ$ as an effective chemical potential, $T_{eff}$ as the effective temperature, and $ξμ$ as the growing free energy barrier for cluster rearrangements.我们研究的发现在持久时间的三十年中是有效的，因此对于理解诸如主动胶体悬浮液或自我推进的颗粒介质等通用活性液体的缓慢动态可能非常有用。
Supercooled liquids display dynamics that are inherently heterogeneous in space. This essentially means that at temperatures below the melting point, particle dynamics in certain regions of the liquid can be orders of magnitude faster than other regions. Often dubbed as dynamical heterogeneity, this behavior has fascinated researchers involved in the study of glass transition, for over two decades. A fundamentally important question in all glass transition studies is whether one can connect the growing relaxation time to a concomitantly growing length scale. In this paper, we go beyond the realm of ordinary glass forming liquids and study the origin of a growing dynamical length scale $ξ$ in a self propelled "active" glass former. This length scale which is constructed using structural correlations agrees well with the average size of the clusters of slow moving particles that are formed as the liquid becomes spatially heterogeneous. We further report that the concomitantly growing $α$- relaxation time exhibits a simple scaling law, $τ_α\sim \text{exp} (ξμ/ T_{eff})$, with $μ$ as an effective chemical potential, $T_{eff}$ as the effective temperature, and $ξμ$ as the growing free energy barrier for cluster rearrangements. The findings of our study are valid over three decades of persistence times, and hence could be very useful in understanding the slow dynamics of a generic active liquid such as an active colloidal suspension, or a self propelled granular medium, to mention a few.
