We present a density functional theory (DFT) for fluids composed of anisometric molecules that may form ordered (liquid-crystalline) phases. Our DFT is based on an augmented modified mean field treatment of pair correlations assuming that the structure of ordered and disordered phases in our model is characterized principally by the repulsive interactions between the spherically symmetric cores of the liquid-crystal molecules. By comparison with corresponding Monte Carlo simulations both in the grand canonical and the isothermal-isobaric ensembles we demonstrate the improvement achieved with our novel approach to describe the pair correlations. The validity of our assumption concerning the structure of the liquid crystal is demonstrated by assessing various orientation dependent pair correlation function by expanding it in terms of rotational invariants.
