The physical significance of time-dependent transition rates

It is shown that physically significant time-dependent transition rates (TDTRs) for dielectric relaxation should be defined to refer to the decay of the system's response function, rather than that of its relaxation function. An examination of the stretched-exponential function in the time domain and of the Havriliak-Negami function in the frequency domain, to which experimental results are often fitted, shows that for most times the TDTRs must be proportional to the inverse of the time. This result is discussed in terms of the difference between global and local TDTRs.