THE DETERMINATION OF LENNARD-JONES POTENTIAL PARAMETERS OF FLUID HYDROGEN-CHLORIDE BY RISM CALCULATIONS OVER A BROAD RANGE OF DENSITIES

Several interaction potentials of (12-6) Lennard-Jones type with added partial point charges were tested for fluid hydrogenchloride. The individual atom pair correlation functions were calculated with the extended RISM theory, and were compared with the weighted superposition of intermolecular atom pair correlation functions that can be determined by a neutron diffraction experiment on fluid deuteriumchloride. Since experimental results are available at the supercritical temperature of 100-degrees-C for densities ranging from 0.5 to 1.1 g.cm-3, the RISM-calculations were performed over that range. By comparing the results of RISM-calculations at different thermodynamic states with experimental results, we show that one can derive an interaction potential that represents the measured structure of the liquid better than potentials derived from measurements at only one thermodynamic state. Finally a new set of Lennard-Jones parameters that leads to a fairly good agreement with the experimental results for all densities is deduced. The individual atom pair correlation functions are given and the dependence on density is discussed.