Phase field crystal model for patchy colloids

斑块胶体的相场晶体模型

• 批准号: 374790102
• 负责人: Professor Dr. Michael Schmiedeberg
• 金额: --
• 依托单位: Lehrstuhl für Theoretische Physik I
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/374790102?language=en
• 关键词: Phase; field; crystal; model; patchy

The goal of the project is to develop and employ a mean field theory for patchy colloids. Patchy colloids are micrometer-sized particles in solution that are decorated with patches that attract patches of neighboring colloids. As a consequence, a huge variety of different periodic and even aperiodic phases is expected that can be achieved by self-assembly. We want to determine these phases, study their properties and explore how they grow.Our mean field approach is motivated by the known static and dynamical phase field models for liquid crystals consisting of particles with axial or polar symmetry. Therefore, the free energy will depend on an order parameter related to the density field and an additional complex order parameter that gives the magnitude as well as the direction of the orientation of the particles. In a first step symmetry considerations are used to construct the free energy expansion in two dimensions. Later our model will be related to expansions obtained by appropriate classical density functional approaches. At the end of the project we want to extend our considerations to three-dimensional systems.The phases are determined by minimizing the free energy. We expect to find complex phases where the structure of the density and that of the orientational field not necessarily have to coincide. Furthermore, even aperiodic structures might occur that possess unique additional degrees of freedom. All major results will be verified by Monte Carlo simulations in case of the static calculations and by Brownian dynamics simulations in case of dynamical phenomena.Our project will not only reveal the complex phase behavior of patchy colloid but also will lead to deeper insights into how complex structures can be stabilized in general: For example, in case of metallic systems, the interactions between atoms might be very complicated involving multiple length scales and preferring specific bond angles. When colloids are considered as model systems for metals, usually isotropic interactions with multiple lengths scales have been studied so far. Our results will improve our knowledge on how bindings angles as an alternative ingredient influences the stability, the static properties, as well as the growth processes of complex structures.

该项目的目标是开发和应用片状胶体的平均场理论。斑块状胶体是溶液中的微米级颗粒，其被吸引相邻胶体的斑块装饰。因此，预期可以通过自组装实现各种不同的周期性甚至非周期性相。我们希望确定这些阶段，研究他们的属性，并探讨他们如何growth.Our平均场方法的动机是由已知的静态和动态相场模型的液晶组成的粒子与轴对称或极对称。因此，自由能将取决于与密度场相关的序参数和给出粒子取向的大小和方向的附加复序参数。在第一步中，对称性的考虑被用来构建在两个维度的自由能展开。稍后，我们的模型将与适当的经典密度泛函方法得到的扩展。在这个项目的最后，我们想把我们的考虑扩展到三维系统，通过最小化自由能来确定相。我们期望找到密度结构和取向场结构不一定一致的复杂相。此外，甚至可能出现具有独特的附加自由度的非周期性结构。所有的主要结果都将在静态计算中通过Monte Carlo模拟进行验证，在动态现象中通过布朗动力学模拟进行验证。我们的项目不仅将揭示斑块状胶体的复杂相行为，还将导致对复杂结构如何稳定的更深入的了解：例如，在金属系统的情况下，原子之间的相互作用可能非常复杂，涉及多个长度尺度和偏好特定的键角。当胶体被认为是金属的模型系统，通常各向同性相互作用与多个长度尺度的研究到目前为止。我们的研究结果将提高我们的知识如何绑定角度作为替代成分影响的稳定性，静态性能，以及复杂结构的生长过程。