Deciphering Transition Pathways in Cholesteric Liquid Crystals
I'm thrilled to delve into the intricate world of cholesteric liquid crystals, a subject at the heart of our recent research. Collaborating with a team of distinguished scientists, we've unveiled new insights into the transition pathways within these captivating materials, specifically focusing on splay mediation and maximally biaxial defect points.
Cholesteric liquid crystals, known for their unique helical structure and optical properties, exhibit a complex dance of molecular alignment and reorientation. Our study reveals two primary ways these crystals transform, each pathway offering a glimpse into the adaptive nature of cholesterics.
The first process, splay mediation, involves a gradual and continuous realignment of molecules. Imagine a slowly twisting ribbon, where each turn represents a subtle shift in the molecular orientation. This process is both elegant and intricate, reflecting the delicate balance in the liquid crystal's structure.
In contrast, the emergence of maximally biaxial defect points is more abrupt, akin to a rapid flick of the ribbon, leading to a noticeable and distinct change. This pathway highlights the dynamic capabilities of cholesterics to respond swiftly to environmental changes.
Our journey to these discoveries was as fascinating as the findings themselves. Utilising advanced, novel analytical techniques and computational modelling, we were able to observe and analyse these transitions in unprecedented detail. Furthermore, we used advanced algorithms to predict the typical optical motifs that would be measured through methods such as polarised light microscopy. This enabled us to provide the expected experimental signatures that would be measured. We proposed both dynamical time evolution signatures and static signatures of the metastable energy minimising states.
The methods employed were not only cutting-edge but also accessible to researchers in the field. By combining numerical techniques with theoretical models, we developed a comprehensive understanding of the cholesteric configuration along the transition pathway of least action. This approach underscores the power of interdisciplinary research in uncovering the secrets of complex materials.
These insights are not just academically intriguing; they have practical implications too. Understanding the mechanisms behind these transitions opens up new possibilities in the design of optical devices, displays, and sensors. Cholesteric liquid crystals, with their unique optical properties, could lead to the development of more efficient and adaptable technologies.
As we continue to explore the fascinating properties of cholesteric liquid crystals, we are constantly reminded of the beauty and complexity of the material world. Our research is a testament to the endless possibilities that emerge when we combine scientific curiosity with collaborative exploration.
To dive deeper into our research and explore the intricate world of cholesteric liquid crystals, I invite you to read our full paper, which provides a more detailed account of our methods and findings.
Discover more by accessing the complete paper at the following link.
https://arxiv.org/pdf/2112.02332.pdf
Exploring Isomorph Invariance in Nanoscale Slitpores: A Personal Journey
As a researcher deeply fascinated by the complexities of material science, I'm excited to share insights from my latest work on 'Isomorph Invariance in Nanoscale Slitpores'. This study is not just close to my heart due to its scientific significance, but also because it represents a confluence of advanced computational techniques and theoretical physics.
At the core of this research lies the concept of isomorphs in the phase diagram. Isomorphs are lines where a system exhibits invariant dynamics and structure when scaled appropriately. They have been described as akin to "Thermodynamic Wormholes". Our study explores this phenomenon within the confines of nanoscale slitpores – channels of widths down to only a few atoms wide, where liquid behaviour is heavily influenced by extreme spatial constraints.
Using the Roskilde University Molecular Dynamics (RUMD) software, specifically optimised for GPU computing, we conducted extensive simulations to understand liquid behaviour inside these slitpores. The high-performance capabilities of Roskilde University's supercomputer played a pivotal role, allowing for simulations that provide a detailed atomistic view of the liquid structures and dynamics under confinement.
One of the key findings of our research was the observation of isomorph invariance in these slitpores. Despite the extreme confinement, the liquids exhibited consistent behaviour along certain isomorphic lines in the phase diagram, a revelation that extends the application of isomorph theory from the bulk to systems exposed to strong levels of confinement.
This work not only advances our theoretical understanding of fluids in confined spaces but also opens up new possibilities in nanotechnology and materials science. It's thrilling to contemplate how these insights could lead to innovations in areas like energy storage, microfluidics, and even pharmaceuticals. The journey into the nanoscopic universe continues, and I am eager to see where it leads us next.
Read the full published paper at the link below.<\p>
arXiv: PDF
arXiv: Supplementary Material
Isomorph Invariance of Higher Order Correlation Functions in Liquids
I am delighted to have been part of a very interesting multi-author research project, collaborating with colleagues from Emory University (USA) and Roskilde University (Denmark), investigating the quasi-universality of higher order structural correlations in various Lennard-Jones systems.
The idea of quasi-universality in liquids has been shown to be evident in a variety of so called ‘Roskilde-Simple’ liquid systems. These are liquids in which there is a notable direct correlation between the instantaneous virial and potential energy of the system. Quasi-universality is evidenced via a collapse of a range of structural and dynamical properties of the system when scaled between statepoints of constant excess entropy, ie; the configurational contributions to the entropy. The existence of quasi-universality has led to such statepoints being referred to as ‘Thermodynamic Wormholes’. These specially density-scaled liquids are however more commonly known as Isomorphs.
Despite much evidence of the collapse of two-point structural correlation functions (RDF) at multiple statepoints relevant to this so-called Isomorph Scaling, an interesting investigation conducted by A. Malins and C. P. Royall et al (2014) seemed to suggest that despite the success of Isomorphic description of the collapse of the RDF, higher-order correlations were not subject the same rules of quasi-universality.
This apparently anomalous behaviour of the Locally Favoured Structure in the Kob-Andersen (KA) system became even more interesting when higher-order correlations were shown to successfully scale in KA systems subjected to high levels of confinement (down to 6 particles in width), albeit at higher temperatures, by BMGD Carter and T. Ingebrigtsen et al (2021).
In order to test this apparent disagreement even further, a project was devised to test the limits of Isomorph Theory and further consider the deviation from the collapse of higher-order (up to twelve-point) correlation functions. It was shown that these structures indeed collapsed when systems were scaled in the appropriate manner. However; we also showed that the 11A (bi-capped square antiprism) structure, which has been deemed to be the Locally Favoured Structure for the supercooled KA system, did indeed not successfully collapse as was determined in 2014.
In order to figure out the interesting devious behaviour, further work will be carried out in an attempt to determine the origin of the discrepancy between two of the wonderful theories describing supercooled liquids.
For more information, read the full open-source manuscript published in the journal ‘Molecules’ at the link below.
https://www.mdpi.com/1420-3049/26/6/1746#