Paul Kallol, Mutneja Anoop, Nandi Saroj Kumar, Karmakar Smarajit
Tata Institute of Fundamental Research Center for Interdisciplinary Science, Hyderabad 500046, Telangana, India.
Proc Natl Acad Sci U S A. 2023 Aug 22;120(34):e2217073120. doi: 10.1073/pnas.2217073120. Epub 2023 Aug 16.
Activity-driven glassy dynamics, while ubiquitous in collective cell migration, intracellular transport, dynamics in bacterial and ant colonies, etc., also extends the scope and extent of the as-yet mysterious physics of glass transition. Active glasses are hitherto assumed to be qualitatively similar to their equilibrium counterparts at an effective temperature, [Formula: see text]. Here, we combine large-scale simulations and an analytical mode-coupling theory (MCT) for such systems and show that, in fact, an active glass is inherently different from an equilibrium glass. Although the relaxation dynamics can be equilibrium-like at a [Formula: see text], effects of activity on the dynamic heterogeneity (DH), which is a hallmark of glassy dynamics, are quite nontrivial and complex. With no preexisting data, we employ four distinct methods for reliable estimates of the DH length scales. Our work shows that active glasses exhibit dramatic growth of DH and systems with similar relaxation times, and thus, [Formula: see text] can have widely varying DH. To theoretically study DH, we extend active MCT and find good qualitative agreement between the theory and simulation results. Our results pave avenues for understanding the role of DH in glassy dynamics and can have fundamental significance even in equilibrium.
活性驱动的玻璃态动力学在集体细胞迁移、细胞内运输、细菌和蚁群动力学等过程中普遍存在，同时也拓展了尚未完全明晰的玻璃态转变物理的范围和程度。活性玻璃迄今被认为在有效温度[公式：见原文]下与平衡态玻璃在性质上相似。在此，我们结合大规模模拟和针对此类系统的解析模式耦合理论（MCT），并表明事实上活性玻璃与平衡态玻璃本质上不同。尽管在[公式：见原文]时弛豫动力学可能类似平衡态，但活性对动态非均匀性（DH）的影响却相当复杂且非平凡，而动态非均匀性是玻璃态动力学的一个标志。由于此前没有相关数据，我们采用四种不同方法来可靠估计DH长度尺度。我们的研究表明，活性玻璃呈现出显著的DH增长，且具有相似弛豫时间的系统，因此[公式：见原文]可能具有广泛不同的DH。为了从理论上研究DH，我们扩展了活性MCT，并发现理论与模拟结果之间有良好的定性一致性。我们的结果为理解DH在玻璃态动力学中的作用开辟了道路，甚至在平衡态下也可能具有根本意义。
