AN ACCURATE THEORETICAL DESCRIPTION OF FLUIDS COMPOSED OF FULLY ANISOTROPIC MOLECULES - APPLICATION TO C-2V SYMMETRY

We use two molecular integral equation approximations to compute the t hermodynamic properties and microscopic structure of two liquids compo sed of planar molecules with C-2v symmetry, namely SO2 and H2S. These approximations couple the exact molecular Ornstein-Zernike equation wi th the hypernetted chain (HNC) and reference-hypernetted chain (RHNC) closures. The theoretical results obtained for various thermodynamic s tates agree remarkably well with molecular dynamics calculations. In p articular, the atom-atom distribution functions are very well reproduc ed. We find that the RHNC approximation with a hard-sphere fluid refer ence system offers notable improvement over HNC in the pressure calcul ation. We include also a self-consistent mean field calculation to inc orporate the effect of polarizability on the dielectric constant of li quid SO2. Final results for this quantity are in excellent agreement w ith experimental values. In contrast, the model used for the electrost atic interactions in H2S leads to anomalously high permanent dipole mo ments, compared to experiment, and consequently to dielectric constant s that an completely off the experimental data. (C) 1997 American Inst itute of Physics.