Calculations of the thermodynamic properties of fluids using many-particle interaction potentials

A method for calculating the thermodynamic properties of fluids with noncentral intermolecular interactions was suggested. The method presupposes the passage from the configurational energy with pair-additive intermolecular interactions depending on the angular orientation of molecules to the configurational energy written in terms of many-particle potentials independent of angular variables. Diatomic fluids with hard-sphere atom-atom potentials, whose configurational energy was represented by two- and three-particle intermolecular interaction potentials, were treated using the theory of integral equations for particle distribution functions. The pressures, isothermal compressibilities, and chemical potentials of the fluids were calculated, and the thermodynamic consistency of the obtained solutions was checked. The method was shown to provide satisfactory accuracy.