Chiral Discotic Columnar Phases in Liquid Crystals

We introduce a model to describe columnar phases of chiral discotic liquid phases in which the normals to disc-like molecules are constrained to lie parallel to columnar axes. The model includes separate chiral interactions favoring, respectively, relative twist of chiral molecules along the axes of the columns and twist of the two-dimensional columnar lattice. It also includes a coupling between the lattice and the orientation of the discotic molecules. We discuss the instability of the aligned hexagonal lattice phase to the formation of a soliton lattice in which molecules twist within their columns without affecting the lattice and to the formation of a moir\'{e} phase consisting of a periodic array of twist grain boundaries perpendicular to the columns.