  A new analytic statistical mechanical model for polar fluids with an
intermolecular pair potential consisting of a hard core and multiple attractive
Yukawa tails has been developed. It includes all the leading terms in the
orientationally averaged electrostatic energies up to quadrupole-quadrupole
interactions. This model is capable of producing analytic expressions for all
the thermodynamic properties of both non-polar and polar fluids. We have
evaluated the Yukawa potential parameters to represent the dispersion potential
from several methods and formulated other Yukawa potentials to represent
electrostatic potentials in simple closed forms, which then could be calculated
directly. Therefore, introducing an arbitrary number of Yukawa potentials does
not introduce any further computational difficulty. Thermodynamic properties of
three representative fluids (argon, carbon dioxide, and methyl chloride) are
predicted with this model. The results indicate good agreement between
experiment and the predictions from this model, given only the Yukawa
intermolecular potential parameters and multipole moments.
