Nematic-Smectic-A-Smectic-CTransitions in Systems of Parallel Hard Molecules

Abstract
The phase diagram for liquid-crystal models of hard molecules is studied by use of a nonlocal density functional for the free energy. Nematic, smectic-A, and smectic-C phases can be obtained from purely packing effects without any attractive interaction. A system of parallel hard spherocylinders shows a continuous phase transition from the nematic to a smectic-A phase, in good agreement with existing computer simulations. In a system of parallel oblique cylinders we predict first- or second-order phase transitions between the smectic-A and the smectic-C phases.