Computer simulation of polar bent-core molecules

Results are presented from molecular dynamics simulations in the NPT ensemble of novel bent-core liquid crystal systems. Following on from a previous study of bent-core steric shape, this study examines the effect the addition of a transverse electric dipole has on the phase diagram of a bent-core liquid crystal model. A simple model of the interaction employed a two-site Gay-Berne potential with the sites separated by +/-0.5 reduced units with a central transverse point dipole, for all models investigated. The angle between the sites 180degrees - gamma was varied in a range gamma = 10degrees to gamma = 70degrees suggested by real molecules. The addition of the dipole to the model tended to stabilize smectic phases and increase the angle of tilted phases. As the angle gamma increased, the transition temperature to the first ordered phase decreased markedly. Smectic A, tilted smectic B, and a spontaneously polarized smectic B phases were observed in the gamma = 10degrees bent-core model. The gamma = 20degrees model showed smectic A and tilted antiferroelectric smectic B phases. The gamma = 40degrees model showed an antiferroelectric phase that exhibited unusual packing behavior. Both the gamma = 20degrees and gamma = 40degrees models demonstrated a significant phase biaxiality in the smectic B phases.