Smectic-A phase of a bidisperse system of parallel hard rods and hard spheres

A binary system of parallel hard spherocylinders and hard spheres are considered to examine influence of addition of spherical molecules to the pure system of rod-like molecules, especially the influence on the structure of the smectic-il phase. Free energy of the system is calculated through the second virial approximation, and nematic-smectic-A transition is estimated by stability analysis of nematic state with sinusoidal density fluctuation. Constant pressure Monte Carlo simulation is also used to confirm a prediction of the stability analysis which prediction indicates that the addition of spherical molecules induces a smectic-A phase as a microphase separation between the spheres and the spherocylinders.