Application of an improved genetic algorithm for fitting X-ray scattering data

摘要

A method of determining parameters of a sample by X-ray scattering comprising the steps ofa) exposing the sample to X-rays and measuring scattered X-ray intensity;b) generating a parameterised model of the sample which is used for numerical simulation of scattered X-ray intensity on the basis of a physical scattering theory;c) comparing the experimental and simulated X-ray scattering data to generate an error value;d) modifying the parameters of the model by means of a genetic algorithm involving an amount of individuals each with an equal number N of encoded parameters forming a generation and applying the genetic operators of "selection", "crossover" and "mutation" used for composing successive generations of evolving individuals, is characterised in that from one generation to the next a "movement" genetic operator is applied which moves at least some of the encoded parameters of at least some of the individuals towards the respective encoded parameters of the individual with the smallest error value. The inventive method improves the genetic algorithm such that it can approximate the true sample parameters faster and with a better reliability.