Structure and freezing of fluids interacting via the Gay-Berne (n-6) potentials

We have calculated the pair-correlation functions of a fluid interacting via the Gay-Berne (n-6) pair potentials using the Percus-Yevick integral equation theory and have shown how these correlations depend on the value of n that measures the sharpness of the repulsive core of the pair potential. These results have been used in the density-functional theory to locate the freezing transitions of these fluids. We have used two different versions of the theory known as the second order and the modified weighted-density-functional theory and examined the freezing of these fluids for 8< or =n< or =30 and in the reduced temperature range lying between 0.65 and 1.25 into the nematic and the smectic A phases. For none of these cases smectic A phase was found to be stabilized though in some range of temperature for a given n it appeared as a metastable state. We have examined the variation of freezing parameters for the isotropic-nematic transition with temperature and n. We have also compared our results with simulation results wherever they are available. While we find that the density-functional theory is good to study the freezing transitions in such fluids the structural parameters found from the Percus-Yevick theory need to be improved particularly at high temperatures and lower values of n.