Dynamical patterns in nematic active matter on a sphere
Dynamical patterns in nematic active matter on a sphere
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DOI：
10.1103/physreve.97.042605
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发表时间：
2018-04-16
影响因子：
2.4
通讯作者：
Sknepnek, Rastko
中科院分区：
文献类型：
--
作者：
Henkes, Silke;Marchetti, M. Cristina;Sknepnek, Rastko
利用近程排斥力和向列相排列的自行剂模拟，我们探索了球表面致密活动向列相的动力学相。我们将非平衡相图映射为曲率、取向强度和活性的函数。我们的模型再现了在最近的实验中看到的几个阶段，这些阶段是限制在囊泡表面的活动微管束。在低驱动下，我们恢复了具有四个+1/2缺陷的平衡向列相基态。随着驱动力的增加，测地线力驱动着向包裹在赤道周围的极带的转变，在赤道两极有两个+1缺陷对应的大的空球帽。随着活性的进一步增加，这些带会自行折叠，系统最终会过渡到以成对的拓扑缺陷扩散为标志的混乱状态。我们强调了在这些具有正高斯曲率的受限系统中，向列相持续长度在控制图案形成中的关键作用。
Using simulations of self-propelled agents with short-range repulsion and nematic alignment, we explore the dynamical phases of a dense active nematic confined to the surface of a sphere. We map the nonequilibrium phase diagram as a function of curvature, alignment strength, and activity. Our model reproduces several phases seen in recent experiments on active microtubule bundles confined the surfaces of vesicles. At low driving, we recover the equilibrium nematic ground state with four + 1/2 defects. As the driving is increased, geodesic forces drive the transition to a polar band wrapping around an equator, with large empty spherical caps corresponding to two +1 defects at the poles. Upon further increasing activity, the bands fold onto themselves, and the system eventually transitions to a turbulent state marked by the proliferation of pairs of topological defects. We highlight the key role of the nematic persistence length in controlling pattern formation in these confined systems with positive Gaussian curvature.