Computational studies of 3D self-assembly of nematic colloids

Nematic colloids are a hybrid soft-matter system consisting of colloidal particles dispersed in a nematic liquid-crystalline host. Colloidal inclusions, which locally perturb nematic ordering, induce energetically unfavourable distortions and topological defects in the nematic medium. The system's drive to minimise free energy via the sharing of costly distortions endow the colloidal particles with highly anisotropic, elasticity-mediated interactions, which can be described in terms of a multipole expansion. In recent years, nematic colloids have emerged as an attractive class of building blocks for colloidal self-assembly with a rich playground for topological design, promising to extend the well-established `colloidal atom' paradigm.

Despite this promise, studies of self-assembly of nematic colloids have largely focused on realising crystal structures in 2D, and a little is known about their phase behaviour in 3D. To address this knowledge gap, we have developed a computational framework for predicting crystal structures for spherical nematic colloids and studying their phase behaviour in 3D, using an effective pair potential that draws contributions from screened electrostatic repulsion and elasticity-mediated interactions under the multipolar approximation. The thesis will describe the development of this computational framework and present case studies to report novel phase behaviour as the effective pair potential is tuned. In certain cases, insight into how the crystal structures are self-assembled will be presented.

1. Our primary impact will be by supplying the UK knowledge economy with skilled multidisciplinary researchers, equipped with the technical and transferable skills to establish the UK as pre-eminent in topology-based future technologies. The training they receive will make them proficient in the demands of the translation of academic science (with a broad background in condensed matter physics, materials science and applied electromagnetics) to industry, with direct experience from internship and industry engagement days. With their exposure to both theoretical research (including modelling and big data-driven problems) and experimental practice, our graduates will be ideally equipped to tackle research challenges of the future and communicate to a broad audience, ready to lead teams made up of diverse specialised components. The potential impact of our researchers will be enhanced by a broad programme of transferable skills, focusing on innovation, entrepreneurship and responsible research. Beneficiaries here will include the students themselves as they embark on future careers intertwining academic research and industry, as well as the other sectors listed below.

2. The research undertaken by students in the CDT will have impact on the future direction of topological science. Related disciplines, including physics, materials science, mathematics, and information technology will benefit from the cross-disciplinary fertilisation it will enable. The CDT will not only provide an interface between research in physical sciences and engineering, but also provide a route for academia to interact effectively with industry. This will help organise researchers from different disciplines to collaborate around the needs of future technology to design materials based on topological properties.

3. Our research will enable industries to set the direction of topological research around the needs of commercial research and development, leading to wealth generation for the UK, and to influence the mindset of the next generation of future technologists. Specifically, topological design has the promise to revolutionise devices and materials relevant to communications, microwave and terahertz technologies, optical information processing, manufacturing, and cybersecurity. Through partnership with organisations from the wider knowledge sector, we will deepen the relationship between academic research and disciplines including IP law and scientific software development.

4. Our CDT will also have impact on the wider academic community. New specialist courses and training in transferable skills will be developed utilising cutting-edge multimedia technologies. Our international research collaborators, including prominent global laboratories, will benefit from placements and research visits of the CDT students. Our interdisciplinary research, combining the needs of academia and industry will be an exemplar of the effectiveness of the CDT model on an international stage.

5. The wider community will benefit from our organised public engagement activities. These will include direct interaction activities, such as demonstrating at the Birmingham Thinktank Science Centre, the Royal Society Summer Exhibition, local schools and community centres.