Dielectric Effects in Dynamical Self-Assembly of Anisotropic Colloids

技术概述化学学部和材料研究学部为本奖项提供资金。它支持胶体粒子在悬浮液中自组装的理论和计算研究和教育，胶体粒子的大小范围在1到1000纳米之间。这是一个引起广泛兴趣的现象，因为它可以创造具有新颖结构的材料。这些系统的计算机模拟通常忽略了溶液中离子和其他带电粒子引起的胶体表面极化电荷的存在。本研究计划的重点是通过开发有效的算法来计算胶体中的介电和感应磁效应，将极化效应纳入理论描述。这些方法将用于理解和预测在外场影响下悬浮介质和磁性胶体的动力学和自组装。PI旨在显著加快计算不同介电常数分离区域表面产生的感应电荷的方法。开发的技术将被扩展到考虑感应磁相互作用，这是一个非常类似的数学形式。所得到的算法将被移植到LAMMPS中，LAMMPS是最广泛使用的分子动力学模拟包之一，也是材料研究界软件网络基础设施的一部分。这种新方法将应用于控制胶体组装，其中随时间变化的外部磁场和电场可以用来诱导相互作用，导致结构远离平衡。这项研究将与实验组密切合作进行。此外，新方法将用于揭示生物系统中的静电结合聚集体如何受到介电失配的影响。特别是，极化电荷对生物稳定性的影响，静电组装聚集体将在一系列系统中进行检查，特别是DNA束。在本研究的背景下所研究的自组装现象将成为本科课程的一部分。这项研究本身将涉及高中生、本科生和研究生。从事研究项目的学生将学习现代计算和理论技术。化学学部和材料研究学部为本奖项提供资金。它支持胶体粒子自组装的理论和计算研究和教育，胶体粒子的大小在1到1000纳米之间，在悬浮液中，一纳米比人类头发的直径小10万倍。自组装可以创造具有新结构和特性的材料。虽然这些系统的计算机模拟现在很常见，但它们绝大多数忽略了胶体表面极化电荷的存在；溶液中的离子和其他带电粒子会引起极化变化。该研究项目将使这些移动介质或极化物体的有效模拟成为可能。新的算法将被开发和应用于设计胶体组装的新方法，其中随时间变化的外加磁场和电场被用来控制自组装。这些方法将用于研究介电效应如何影响生物系统中的静电聚集。提出的模拟方法将产生超出本项目范围的影响，使研究从软凝聚态系统到生物相关解决方案的广泛系统类别成为可能。此外，本研究所研究的自组装现象将成为本科课程的一部分。这项研究将涉及高中生、本科生和研究生。

TECHNICAL SUMMARYThe Chemistry Division and Division of Materials Research contribute funds to this award. It supports theoretical and computation research and education on the self-assembly of colloidal particles, objects with sizes in the range 1 to 1000 nanometers, in suspension. This is a phenomenon of widespread interest, as it enables creation of materials with novel structures. Computer simulations of these systems usually ignore the presence of polarization charges at the surfaces of the colloids, induced by ions and other charged particles in solution. This research program focuses on including polarization effects in the theoretical description by developing efficient algorithms to calculate dielectric and induced magnetic effects in colloids. These methods will be used to understand and predict the dynamics and self-assembly of suspended dielectric and magnetic colloids under the influence of the external fields. The PI aims to significantly accelerate methods to compute induced charges that arise at surfaces separating regions of different dielectric constant. The developed techniques will be extended to account for induced magnetic interactions, which are subject to a very similar mathematical formalism. The resulting algorithm will be ported to LAMMPS, one of the most widely used molecular dynamics simulation packages and part of the software cyberinfrastructure of the materials research community.This new methodology will be applied to control colloidal assembly, in which time-dependent external magnetic and electric fields could be used to induce interactions resulting in structures far from equilibrium. This research will be conducted in close collaboration with experimental groups. Furthermore, new methods will be used to uncover how electrostatically bound aggregates in biological systems are affected by dielectric mismatch. In particular, the effect of polarization charges on the stability of biological, electrostatically assembled aggregates will be examined for a range of systems, notably DNA bundles. The self-assembly phenomena studied in the context of this research will become a part of the undergraduate classes. The research itself will involve high-school students, undergraduates, and graduate students. Students working on research projects will learn modern computational and theoretical techniques. NONTECHNICAL SUMMARYThe Chemistry Division and Division of Materials Research contribute funds to this award. It supports theoretical and computation research and education on the self-assembly of colloidal particles, objects with sizes in the range 1 to 1000 nanometers, in suspension, a nanometer is about 100,000 times smaller than the diameter of a human hair. Self-assembly enables the creation of materials with novel structures and properties. Whereas computer simulations of these systems are now commonplace, they overwhelmingly ignore the presence of polarization charges at the surfaces of the colloids; polarization changes arise in response to ions and other charged particles in the solution. This research project will make possible the efficient simulation of these mobile dielectric or polarizable objects.New algorithms will be developed and applied to design new approaches to colloidal assembly, in which applied magnetic and electric fields that vary in time are used to control self-assembly. These methods will be used to study how dielectric effects affect electrostatic aggregation in biological systems.The proposed simulation methods will have an impact beyond the scope of this project by enabling the study of broad classes of systems ranging from soft condensed-matter systems to biologically relevant solutions. Furthermore, the self-assembly phenomena studied in the context of this research will become part of undergraduate classes. The research will involve high-school students, undergraduates, and graduate students.