Effective Spherical Potentials for Molecular Fluid Thermodynamics

Abstract

Through a thermodynamic perturbation expansion, a new sphericalization procedure has been obtained for anisotropic molecular potentials. For ${\mathrm{N}}_2$ the resulting fluid pressures and internal energies for the effective spherical potential differ at high densities by at most 1.5% from exact molecular-dynamics calculations for the anisotropic ${\mathrm{N}}_2$ potential. Results at lower densities are comparably good. Preliminary results for C${\mathrm{O}}_2$, an even more anisotropic molecule, are also excellent.