Modeling hard ellipsoid in the context of glass

The hard-sphere model has significantly propelled advancements in colloidal science. Now, the interest has moved to its more general counterpart, hard ellipsoids. Despite their relative simplicity, hard ellipsoids can reveal a rich phase diagram, such as liquid crystals, that has already found several applications in materials engineering.

In our research, we investigate the effect of introducing softness to model the interactions in ellipsoidal colloids studied in the AG Zumbusch at our university. We seek to understand the differences in the phase diagrams of hard ellipsoids and soft ellipsoids, which appear in the phase transitions of both systems, especially in the isotropic-nematic phase transition.
Additionally, we are determining the criteria and conditions that can lead to the liquid glass state which was experimentally proven in "Observation of liquid glass in suspensions of ellipsoidal colloids" by Jörg Roller, Aleena Laganapan, Janne-Mieke Meijer, Matthias Fuchs, and Andreas Zumbusch.

We use the Large-scale Atomic/Molecular Massively Parallel Simulator, LAMMPS, to carry out molecular dynamic simulations in order to probe the phase space of soft ellipsoids. For the hard ellipsoids, we use event-driven Brownian dynamics simulations. Our simulations are based on analyzing the results of pair correlation functions, structure factors and their orientation counterpart functions. Moreover, we study the dynamics of the system by computing the self intermediate scattering function and angular correlation functions which are defined in the context of Legendre polynomials.

Another aim of our research project is to understand the dynamics of ellipsoids experiencing external torques. This research enables us to discover the relation between translation and rotational diffusion of ellipsoidal systems inside a background solvent. This will give us insight on dynamics of artificial or natural colloids that move and rotate in different environments such as cells in the blood.

Overall, it is our aim to develop simulation models that link and elucidate several research areas such as the physics of protein inside the human body, liquid crystal phases, and glassy dynamics.