Crystal Structure Solution as an Optimization Problem: a Genetic Algorithm for Direct Space Structure Solution from Powder Diffraction Data

Roy L. Johnston, Benson M. Kariuki and Kenneth D. M. Harris

School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, U.K.

Article: in Fashioning a Model: Optimization Methods in Chemical Physics (Eds. A. Ernesti, J. M. Hutson and N.J. Wright), CCP6, Daresbury, 1998, 41-47.

Abstract

In this paper we present a brief overview of our implementation of a Genetic Algorithm for solving crystal structures directly from powder diffraction data. Structure solution is shown to correspond to a global optimization problem, in which we wish to minimize the measure of disagreement between a calculated and an experimental powder diffractogram. In this approach, a population of trial structures is allowed to evolve subject to well-defined rules governing mating, mutation and `natural selection'. The `fitness' of each structure in the population is a function of its profile R-factor.


Write or e-mail me (roy@tc.bham.ac.uk) for a reprint.