Applications of Evolutionary Computation in Structure Determination from Diffraction Data

Evolutionary algorithms are finding increasing use in the study of a wide range of different types of diffraction data. In this chapter, we review recent applications of evolutionary algorithms to study a variety of structural problems. Examples range from the study of disordered materials by analysis of diffuse scattering data to molecular replacement techniques in biological crystallography. However, the main focus of this chapter is on the application of genetic algorithms in the determination of crystal structures directly from powder diffraction data. The principles underlying the application of genetic algorithm techniques in structure determination from powder diffraction data are described, and applications of this methodology to determine molecular crystal structures of considerable complexity are also highlighted. Clearly the opportunity to determine crystal structures directly from powder diffraction data provides a vital alternative to single-crystal X-ray diffraction, when single crystals of appropriate size and quality for single-crystal diffraction cannot be prepared for the material of interest.