Simulation of cholesteric systems in bulk and in confined settings using a coarse-grained model on pitch level

• Applicant: Dr. Anja Kuhnhold
• Subject Area: Statistical Physics, Nonlinear Dynamics, Complex Systems, Soft and Fluid Matter, Biological Physics
• Term: from 2020 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 435320238

Cholesteric liquid crystals are focused on by many scientific projects. Based on their special optical properties interesting options for applications unfold, like invisible sensors or flexible displays. Most of the projects, that address this exciting topic, are of experimental kind.To expand the field of application of simulations of cholesteric systems we will develop a coarse-grained model on the cholesteric pitch level. Background to this aim is that simulations on the molecular level can only represent a small section of space. Thus, experimentally relevant length scales are only hard to reach. To perform the coarse-graining we use correlations that we found in simulations on the molecular level. The result will be a coarse-grained “cholesteric particle”, that includes the cholesteric pitch as an attribute. Using the pair interaction of those cholesteric particles we can conduct simulations on the coarse-grained level.During the method development we will use hard rods with a simple chiral interaction as model system. The coarse-graining method will then be applied to further model systems (special chiral interaction and helical Yukawa rods). We study the phase behavior of the coarse-grained systems and compare to experimental and previous simulation results. In addition we will investigate the influence of confining environments like tactoids (spindle-like droplets) or spherical shells on the cholesteric system. These are the groundwork for further fascinating applications of cholesteric liquid crystals, like e.g. individual labels for counterfeit protection.All in all the aspired project serves for providing technologically relevant predictions. The understanding of relations between molecular parameters and macroscopic features is essential for efficient material design. In particular, the project contributes to enhance the control of the optical properties of cholesteric systems.

• DFG Programme: Research Grants