Sinha Arpan, Chaudhuri Debasish
Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005, India.
Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400094, India.
Soft Matter. 2024 Oct 16;20(40):8078-8088. doi: 10.1039/d4sm00775a.
Using the Lebwohl-Lasher interaction for reciprocal local alignment, we present a comprehensive phase diagram for a dry, apolar, active nematic system using its stochastic off-lattice dynamics. The nematic-isotropic transition in this system is first-order and occurs alongside a fluctuation-dominated phase separation. Our phase diagram identifies three distinct regions based on activity and orientational noise relative to alignment strength: a homogeneous isotropic phase, a nematic phase with giant density fluctuations, and a coexistence region. Using mean-field analysis and hydrodynamic theory, we demonstrate that reciprocal interactions lead to a density fluctuation-induced first-order transition and derive a phase boundary consistent with numerical results. Quenching from the isotropic to nematic phase reveals coarsening dynamics where nematic ordering precedes particle clustering. Both the nematic and density fields exhibit similar scaling behaviors, exhibiting dynamic exponents ≈ 2.5 and ≈ 2.34, consistently falling within the range of 2 and 3.
利用Lebwohl-Lasher相互作用进行互易局部比对，我们使用其随机非格点动力学，给出了一个干燥、非极性、活性向列体系的完整相图。该体系中的向列 - 各向同性转变是一级相变，且与涨落主导的相分离同时发生。我们的相图基于活性和相对于排列强度的取向噪声，确定了三个不同区域：均匀各向同性相、具有巨大密度涨落的向列相以及共存区域。通过平均场分析和流体动力学理论，我们证明互易相互作用会导致密度涨落诱导的一级相变，并推导出与数值结果一致的相边界。从各向同性相猝灭到向列相揭示了粗化动力学，其中向列有序先于粒子聚集。向列场和密度场都表现出相似的标度行为，动态指数分别约为2.5和约为2.34，始终落在2到3的范围内。
