ORDERING OF HARD NEEDLES AT A HARD-WALL

We study a system of hard spherocylinders in contact with a hard wall, assuming that the length-to-width ratio of the spherocylinder tends to infinity. The Onsager approximation is applied to calculate the free energy of the system. The integral equation for the one-particle distribution function is solved in the uniaxial case, i.e., for bulk densities corresponding to the isotropic phase. We find the density and order parameter profiles and conclude that the particles prefer parallel alignment close to the wall. Finally, we study the stability of the uniaxial solution and find the bifurcation point corresponding to the nematic order close to the wall.