GAS-LIQUID COEXISTENCE PROPERTIES FROM REFERENCE HYPERNETTED-CHAIN THEORY FOR LINEAR POLAR-SOLVENTS

Hydrogen chloride and acetonitrile are both well characterized polar s olvents whose constituent molecules either are linear or can be well a pproximated in such a way. Here we present a theoretical study of thei r gas-liquid coexistence properties by means of a reference hypernette d chain integral equation. The standard two and three-center Lennard-J ones models are reformulated on the basis of the integral equation pre diction of the coexistence curve, so that the new models describe more precisely the experimental critical properties. Extensive Gibbs ensem ble Monte Carlo simulations confirm the reliability of the theoretical estimates and the adequacy of the model. Besides, both X-ray and neut ron-diffraction structure factors are accurately reproduced, and a com parison with simulation results for a six-center model for CH3CN also endorses the suitability of the three-center linear model for this sub stance.