Density functional approximation for hard-body liquid crystals

We present a density functional approximation for the free energy of a system of hard bodies with arbitrary shape and orientational distribution. For systems with homogeneous density it reduces to existing treatments, which describe the isotropic liquid and the nematic liquid crystal. The treatment of the inhomogeneous density allows the study of smectic and crystal phases. We applied the approximation to a system of parallel hard spherocylinders, for which we compare the nematic to smectic-A phase transition with recent computer simulation data. We also study a system of oblique cylinders and show that smectic-C phase may appear as the result of packing effects in systems of hard bodies.