The interplay between shape anisotropy and directed long-range interactions enables the self-assembly of complex colloidal structures. As a recent highlight, ellipsoidal particles polarized in an external electric field were observed to associate into well-defined tubular structures. In this study, we systematically investigate such directed self-assembly using Monte Carlo simulations of a two-point-charge model of polarizable prolate ellipsoids. In spite of its simplicity and computational efficiency, we demonstrate that the model is capable of capturing the complex structures observed in experiments on ellipsoidal colloids at low volume fractions. We show that, at sufficiently high electric field strength, the anisotropy in shape and electrostatic interactions causes a transition from three-dimensional crystal structures observed at low aspect ratios to two-dimensional sheets and tubes at higher aspect ratios. Our work thus illustrates the rich self-assembly behavior accessible when exploiting the interplay between competing long- and short-range anisotropic interactions in colloidal systems.

中文翻译：

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可极化椭球在外部电场中的定向自组装

形状各向异性和定向的远程相互作用之间的相互作用使复杂的胶体结构能够自组装。作为最近的亮点，观察到在外部电场中极化的椭圆形颗粒与明确定义的管状结构缔合。在这项研究中，我们系统地使用极化极化椭球体两点电荷模型的蒙特卡洛模拟系统研究了这种定向自组装。尽管其简单性和计算效率，我们证明该模型能够捕获在低体积分数的椭球胶体实验中观察到的复杂结构。我们表明，在足够高的电场强度下，形状和静电相互作用的各向异性导致从以低长宽比观察到的三维晶体结构过渡到以高长宽比观察到的二维片材和管材。因此，我们的工作说明了利用胶体系统中竞争的长程和短程各向异性相互作用之间的相互作用时可访问的丰富的自组装行为。