椭球粒子二元混合物中的两阶段有序化动力学

中文摘要 AI 辅助

我们利用大规模分子动力学模拟，研究了通过各向异性Gay-Berne势相互作用的单轴椭球粒子二元混合物的非平衡相有序化动力学。在从各向同性均匀相温度淬火进入共存区后，系统表现出两个发生在不同时间尺度上的不同有序化过程。首先，快速的取向有序化导致向列畴的形成和粗化，其特征是动力学标度、广义Porod定律行为以及与非守恒序参量动力学一致的生长律$\ell(t) \sim t^{1/2}$。随后，系统经历由组分涨落驱动的二元相分离。这一组分有序化过程表现出从扩散生长$\ell(t) \sim t^{1/3}$到流体动力学区域的转变，有限尺寸标度分析表明渐近粘性生长$\ell(t) \sim t$。尽管存在全局取向序，相分离动力学仍保持有效各向同性。这些结果证明了取向和组分有序化动力学之间的清晰分离，它们受不同的守恒定律支配，并为理解各向异性粒子系统中的相有序化提供了统一框架。

英文摘要

We investigate the nonequilibrium phase-ordering kinetics of a binary mixture of uniaxial ellipsoidal particles interacting via the anisotropic Gay-Berne potential using large-scale molecular dynamics simulations. Following a temperature quench from the isotropic and homogeneous phase into the coexistence region, the system exhibits two distinct ordering processes occurring on different time scales. At first, rapid orientational ordering leads to the formation and coarsening of nematic domains, characterized by dynamical scaling, generalized Porod-law behavior, and a growth law $\ell(t) \sim t^{1/2}$ consistent with nonconserved order-parameter dynamics. Later, the system undergoes binary phase separation driven by compositional fluctuations. This compositional ordering process shows a transition from diffusive growth $\ell(t) \sim t^{1/3}$ to hydrodynamic regimes, with finite-size scaling analysis indicating asymptotic viscous growth $\ell(t) \sim t$. Despite the presence of global orientational order, the phase-separation kinetics remains effectively isotropic. These results demonstrate a clear separation between orientational and compositional ordering dynamics, governed by distinct conservation laws, and provide a unified framework for understanding phase ordering in anisotropic particle systems.

发表机构

• Vellore Institute of Technology（维罗尔理工大学）
• Jawaharlal Nehru University（贾瓦哈拉尔·尼赫鲁大学）
• Indian Institute of Science Education and Research Berhampur（贝拉姆普尔印度科学教育研究所）

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