PERTURBATION-THEORY OF POLAR NONSPHERICAL MOLECULE FLUIDS

Perturbation theory of polar nonspherical molecule fluids was applied to systems of dipolar and polarizable dipolar Kihara molecules. Integrals corresponding to the first, second and third order perturbation terms, containing the angle-dependent part of the electrostatic pair potentials, were determined by the numerical methods for a set of parameters characterizing the nonsphericity of molecules, and expressed in the form of Pade approximants. Theoretical expressions for thermodynamic functions were applied to describe the dipolar nonspherical molecule system and compared with the simulation data. Simple models of polarizable quadrupolar and polarizable dipolar Kihara molecule fluids were considered for carbon dioxide and hydrogen chloride and theoretical expressions for the Helmholtz function, compressibility factor and the second virial coefficient were employed to describe the equilibrium behaviour of these systems. Comparison with experimental data is given.