Orientation-averaged pair correlations in a molecular theory of nematic liquid crystals

A molecular theory of nematic liquid crystals is presented in which the short-range spatial correlations are accounted for by an orientation-averaged pair correlation function. This results in a two-fold self-consistency scheme whose spatial description resembles that in the conventional theory of classical liquids and whose orientational description resembles a mean-field theory. Numerical calculations are made for a simple potential chosen to describe para-azoxyanisole (PAA). Among the properties calculated are the two-phase coexistence curve, the order parameter along the coexistence curve, temperature dependence of the order parameter at constant pressure, and volume change and latent heat at the isotropic-nematic transition. Comparison with experimental data is made. There are encouraging signs to warrant further investigation.