Correlation Function Theory of Dielectric Relaxation

The Kubo formalism is developed for polarizable dipolar molecules treated as harmonic oscillators in the relaxation counterpart of Kirkwood's equilibrium theory. Treatment of reaction field induced moments as in Onsager's model gives a generalization of the relaxation time ratio 3ε0/(2ε0+ε∞) proposed by Powles. The correlation function expression for relaxation is evaluated for several models: rotational transition probabilities including diffusion, nonequivalent dipole orientation sites, and flexible molecules with internal dipole reorientations.