On the derivation of the Debye theory of dielectric relaxation from the Langevin equation in the presence of the driving field

It is shown how the Debye results for the behavior of an assembly of dipoles subjected to step-on, step-off, and ac fields which are usually obtained by calculating the linear response from the Smoluchowski equation may also be obtained from the Langevin equation by using a transformation of that equation suggested by Frood and Lal. This transformation allows one to calculate the linear response from the Langevin equation even in the presence of a driving field.