Structures, Thermodynamics and Dynamics of Topological Defects in Gay–Berne Nematic Liquid Crystals*

As a consequence of broken symmetry, topological defects are ubiquitous across different physical systems, and are thereby important for understanding a wide variety of phenomena in physics. In nematic liquid crystals, topological defects exhibit unique optical signatures and can segregate impurities, showing their promise as molecular carriers and nano-reactors. Therefore, understanding defect structures and dynamics in liquid crystals is essential for their further applications. In this work, we study the structure and dynamics of topological defects in Gay–Berne nematic liquid crystals by molecular dynamics simulations. The elastic bend-to-splay ratio is measured using two independent measurements, showing good agreement with literature. Next, we study defect annihilation event, and find that their trajectories are consistent with experiments and hydrodynamic simulations. We further examine the thermodynamics of the system before and after defect annihilation, the result of which can be used to estimate the elastic constant of the nematic. Finally, we study defect motion under a temperature gradient and find that defects tend to propel into hotter area. Taken together, our work has provided molecular roots of continuum theory and simulations and proposed an alternative control parameter for defect transport.