Theory and simulation of the cubatic liquid crystalline phase

立方液晶相的理论与模拟

• 批准号: EP/D001730/1
• 负责人: Andrew Masters
• 金额: $ 13.15万
• 依托单位: University of Manchester
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2006
• 资助国家: 英国
• 起止时间: 2006 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FD001730%2F1
• 关键词: Theory; simulation; cubatic; liquid; crystalline

The cubatic liquid crystalline phase is a most extraordinary state of matter. The molecules have no long-range positional order but the orientations exhibit a cubic symmetry. This phase has been observed in the simulation of truncated hard spheres. Each particle points, on average, along one of the x-, y- or z-axes with equal probability. Because this symmetry is completely different from that of other known phases, the material properties of this phase will also be very different. Virtually no research, however, has been carried out on this phase, so this proposal aims to rectify this situation. The aim is to use simulation and theory to provide the scientific foundations for describing the behaviour of this exotic state of matter.In more detail, we will firstly carry out Monte Carlo simulations to map out the boundaries of the cubatic phase for truncated spheres. We will then calculate the cubatic elastic constants and, knowing these, go on to study inhomogeneous situations, such as the structure of defects, the structure of the material near a wall and the interactions with colloidal spheres. We will interpret these simulation studies using cubatic elastic theory, which will be developed in tandem with the simulation work.We will study also, for the first time, the dynamical properties of this phase. Using molecular dynamics, we will look at the cubatic transport coefficients and a variety of time correlation functions. These will be compared with Enksog kinetic theory calculations. After this we will investigate the effects of shearing a cubatic phase, looking for shear induced phase transitions. At equilibrium the cubatic phase has nematic, columnar and crystalline phases as close neightbours, so one would expect a rich crop of flow-induced transitions.The overall aim of this work is to produce a body of fundamental work, giving the basic framework for understanding the fundamental properties of this unexplored state of matter,

立方相液晶是一种非常特殊的物质状态。分子没有长程位置顺序，但取向表现出立方对称性。在截断硬球的模拟中已经观察到这个阶段。平均而言，每个粒子以相等的概率沿着x轴、y轴或z轴之一指向。由于这种对称性与其他已知相的对称性完全不同，因此该相的材料性质也会有很大不同。然而，几乎没有对这一阶段进行过研究，因此本提案旨在纠正这种情况。我们的目标是用模拟和理论来提供科学的基础来描述这种奇异的物质状态的行为。更详细地说，我们将首先进行蒙特卡罗模拟来绘制截断球的立方相的边界。然后，我们将计算立方弹性常数，并知道这些，继续研究非均匀的情况下，如缺陷的结构，结构的材料附近的一个墙和相互作用与胶体球。我们将使用与模拟工作同步发展的立方弹性理论来解释这些模拟研究。我们还将首次研究该相的动力学性质。利用分子动力学，我们将研究立方输运系数和各种时间相关函数。这些将与Enksog动力学理论计算进行比较。在此之后，我们将研究剪切立方相的影响，寻找剪切诱导相变。在平衡状态下，立方相具有紧密相邻的柱状、柱状和结晶相，因此人们会期望大量的流动诱导转变。这项工作的总体目标是产生一系列基本工作，为理解这种未探索的物质状态的基本性质提供基本框架，