ISGP: Impedance Spectroscopy Analysis Using Evolutionary Programming Procedure

Impedance spectroscopy (IS) measurement results in a complex function over several orders of magnitude of frequencies. The underlying physical phenomena are related to the relaxation times in the sample. The inverse problem of finding the distribution function of relaxation times (DFRT) is a demanding one. We have developed a modified Genetic Programming (GP) method for this task. It gives a functional form of the DFRT in the sample. The evolution force is composed of lowering the discrepancy between the model's prediction and the measured data, while keeping the model simple in terms of the number of free parameters. The program seeks DFRT that has the form of a peak or a sum of several peaks, assuming the Debye kernel. All the peaks are known functions. By finding a functional form of the DFRT, one may develop a physical model and examine its behavior. The different peaks, which can be related to different processes, can be analyzed separately.