Effective Spherical Potentials for Molecular Fluid Thermodynamics

Through a thermodynamic perturbation expansion, a new sphericalization procedure has been obtained for anisotropic molecular potentials. For N₂ 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 N₂ potential. Results at lower densities are comparably good. Preliminary results for CO₂, an even more anisotropic molecule, are also excellent.