Structure and thermodynamics of liquid acetonitrile via Monte Carlo simulation and Ornstein-Zernike theories

Acetonitrile is modeled by a system of three sites, which are the centres of short-range Lennard-Jones interactions and which carry partial electric charges. Site-site distribution functions, internal energies, and dielectric constants are computed, using three theoretical methods: Monte Carlo simulation, molecular Ornstein-Zernike theory and site-site Ornstein-Zernike theory. The results of these calculations are compared and discussed in the light of the approximations inherent in the various approaches. The molecular pair distribution function is analysed to find pair configurations occuring in the liquid with a high probability The effects of these configurations on the thermodynamic and structural properties are studied.