Hydrodynamics of biaxial discotics

Abstract

The nonlinear hydrodynamic equations for biaxial discotics with two broken translational symmetries (which have been identified experimentally very recently) are presented and the structure of the hydrodynamic excitations is considered. For biaxial discotics with broken rotational symmetries, owing to the existence of two preferred axes, the gradient free energy, representing a generalization of the Frank free energy for nematic liquid crystals, is given and the nonlinear hydrodynamic equations are derived. As a striking result a set of three commutator-type relations reflecting the anholomomity of the hydrodynamic variables characterizing the broken symmetries is found for the first time in the physics of liquid crystals. The influence of a static external magnetic field on both types of biaxial discotics is discussed.