Angular correlations and statistical entropy of hard spherocylinders: the isotropic-nematic transition

We calculate, using standard constant-pressure Monte Carlo techniques, the statistical entropy of a system of hard spherocylinders and resolve the contribution of two-body correlations into a translational and an orientational part within the framework of a multiparticle correlation expansion of the configurational entropy. We find that the residual term, that is cumulatively associated with correlations involving more than two particles, bears a neat signature, when plotted as a function of the density, of the impending transition of the isotropic fluid into a nematic phase. We show that this one-phase structural indication of the isotropic-nematic transition is ascribed to the angular contribution in the pair entropy of the fluid.