Advanced Algorithms for Colloids with Induced Many-Body Interactions

该奖项支持计算和理论研究，重点是开发使用计算机模拟的新方法来理解悬浮在另一介质中的胶体颗粒的自组装，胶体颗粒的大小范围在1到1000纳米之间。它们可以作为构建新材料的基石，通过外部电场和磁场来重新配置和调谐，这已成为当前材料科学与工程的重要焦点。这种材料有广泛的应用，但人们对构成这种材料的各个组成部分如何响应随时间变化的场（比如由交流电供电的电磁铁产生的场）知之甚少。PI和他的研究团队正在开发新的计算方法，以前所未有的精度预测和理解这些特性，为设计响应材料开辟了道路。同样的算法也可以用来理解和改进微流体装置，其中微量的流体被操纵，例如用于分析目的。本项目开发的计算方法将集成到材料和其他研究界广泛使用的计算机模拟软件包中。PI将继续维护一个Wiki，提供他的团队开发的计算工具，这已经成为更广泛的计算研究社区的资源。该奖项支持计算和理论研究，重点是开发和应用加速算法，这些算法可以解释由电和磁极化引起的诱导多体相互作用。这些方法将用于探索和理解各向异性胶体在外场中的新的动力学行为，并设计靶向自组装的构建块。悬浮液中胶体粒子的动力学和自组装引起了广泛的兴趣，因为它们允许创造具有新结构的材料。直到最近才有算法可以模拟这些现象，同时考虑到完全分解的表面极化。PI现在将利用这种方法来探索和理解各向异性胶体在外场中的行为，在外场中，双电层被扭曲，引起诱导的相互作用，甚至导致集体动力学的推进。此外，该算法将扩展到体极化率，这是一种迄今为止几乎没有进行过计算探索的现象，以及一种混合方法，该方法将使重要类别的介电模型系统的模拟速度比目前可能的速度提高两个数量级。软质材料的计算机模拟现在通常考虑到远距离静电相互作用。介质失配在自然界中普遍存在，但由于其计算复杂性而被忽略，近年来人们越来越重视它的作用。在NSF的支持下，PI开发了一项研究计划，该计划提供了一种实际可用的边界元素方法，能够处理移动介质物体。目前的项目应用这种方法来理解活性物质模型系统中的推进机制和微流体装置中的电渗透流动行为。此外，体电介质等效算法的发展将使由于缺乏适当的计算技术而几乎未被探索的材料行为的研究成为可能。这项研究是及时的，因为对胶体相互作用的控制是可重构材料发展的焦点。计算方法和资源现在能够为实验提供直接指导。本文提出的进展将大大扩展现有的能力，并阐明动态集体现象以及由诱导相互作用驱动的自组装。本项目开发的计算方法将集成到材料和其他研究界广泛使用的计算机模拟软件包中。PI将继续维护一个Wiki，提供他的团队开发的计算工具，这已经成为更广泛的计算研究社区的资源。

NONTECHNICAL SUMMARYThis award supports computational and theoretical research with a focus on developing new ways to use computer simulation to understand self-assembly of colloidal particles, objects with sizes in the range 1 to 1000 nanometers, suspended in another medium. They can be used as building blocks to create new materials that can be reconfigured and tuned by means of external electric and magnetic fields, which has become an important focal point of current materials science and engineering. Such materials find a wide range of applications, but it is poorly understood how the individual building blocks making up the material respond to fields that vary over time, such as those generated by electromagnets powered by alternating currents. The PI and his research team are developing novel computational methods that make it possible to predict and understand such properties with unprecedented accuracy, opening the way to designing responsive materials. The same algorithms also can be employed to understand and improve microfluidic devices, in which minute amounts of fluids are manipulated, for example for analytic purposes.Computational methods developed by this project will be integrated into computer simulation packages widely used by the materials and other research communities. The PI will continue to maintain a Wiki that provides computational tools developed in his group which has become a resource to the broader computational research community.TECHNICAL SUMMARYThis award supports computational and theoretical research focused on the development and application of accelerated algorithms that account for induced many-body interactions that arise from electric and magnetic polarizability. These methods will be used to explore and understand new dynamical behavior of anisotropic colloids in external fields, and to design building blocks for targeted self-assembly. The dynamics and self-assembly of colloidal particles in suspension are of widespread interest, as they allow the creation of materials with novel structures. Only recently have algorithms become available that make it possible to simulate these phenomena while taking into account fully resolved surface polarization. The PI will now exploit this approach to explore and understand the behavior of anisotropic colloids in external fields, where the electric double layer is distorted, giving rise to induced interactions or even propulsion that results in collective dynamics. Moreover, the algorithms will be extended to bulk polarizability, a phenomenon that until now has barely been explored computationally, and to a hybrid method that will accelerate the simulation of important classes of dielectric model systems by two orders of magnitude compared to what is currently possible.Computer simulations of soft materials now routinely take into account long-range electrostatic interactions. In recent years increasing attention has been devoted to the role of dielectric mismatch ubiquitous in nature but traditionally ignored owing to its computational complexity. With prior NSF support, the PI has developed a research program that has delivered a practically usable boundary-element method capable of dealing with mobile dielectric objects. The current project applies this method to understand the propulsion mechanism in model systems of active matter and the behavior of electro-osmotic flow in microfluidic devices. Moreover, the development of an equivalent algorithm for bulk dielectrics will enable the study of materials behavior that has been virtually unexplored for want of appropriate computational techniques.This research is timely because control over colloidal interactions is a focal point in the development of reconfigurable materials. Computational methods and resources are now able to provide direct guidance to experiments. The advances proposed here will significantly extend existing capabilities and elucidate dynamic collective phenomena as well as self-assembly driven by induced interactions.Computational methods developed by this project will be integrated into computer simulation packages widely used by the materials and other research communities. The PI will continue to maintain a Wiki that provides computational tools developed in his group which has become a resource to the broader computational research community.