Correlation function for relaxations in disordered materials

An empirical relaxation function suitable for describing the dynamics in disordered materials is presented. The function is a generalization of the stretched exponential function and based on power-law decays. The influence of parameters on the shape of the correlation function is discussed. Numerically transformed data are compared with some of the most commonly used curve–fit functions in the frequency dependent susceptibility. It is shown that a special case of the function is an approximation of the correlation function corresponding to the Cole–Cole function [K. S. Cole and R. H. Cole, J. Chem Phys. 9, 341 (1941)]. The applicability of the correlation function to describe glass transition dynamics is also discussed. Finally, it is shown that the proposed relaxation function can provide a significant improvement in the description of experimental data.