The second dielectric virial coefficient of multipolar hard spheres

Abstract

The second dielectric virial coefficient, B _∈ ^*, is calculated for a fluid of hard spheres with dipole, quadrupole, octopole and hexadecapole moments. It is very sensitive to both the signs and magnitudes of these moments, and for realistic molecular values may either be very large and positive or very large and negative. It is suggested that a one centre multipole expansion of the molecular charge distribution will not yield a convergent value either for B _∈ ^* or ∈ of a dense fluid, and that attempts to calculate the dielectric constant of a real fluid should be based upon multicentre multipole expansions, incorporated into a theory such as Chandler and Andersen's ISM.