Unified model of the smectic-A, nematic, and isotropic phases for bulk, interfaces, and thin films: Bulk

A lattice model for three liquid crystalline phases is presented and solved in the mean-field approximation. Numerical results are obtained for the bulk phases. We find isotropic, nematic, and smectic-A phases, with the possibility of nematic-isotropic, smectic-A--isotropic, and nematic--smectic-A (NS) transitions. The NS transition can be first or second order, depending upon the choice of molecular potential. Examples modeling the materials octyl-oxycyanobiphenyl (8OCB) and cholersteryl myristate are considered