Solving a Structure in the Reciprocal Space, Real Space and Both by Using the EXPO Software

The solution of crystal structures from X-ray powder diffraction data has undergone intense development in the last 25 years. Overlapping, background estimate, and preferred orientation are the main difficulties in the process of determining a crystal structure from the analysis of the mono-dimensional powder diffraction pattern. EXPO is a well-known computer program that is designed to solve organic, inorganic, and metal&ndash
organic structures by powder diffraction data, employing the two most widely used kinds of solution methods: Direct Methods, working in the reciprocal space
and Simulated Annealing, working in the real space. EXPO also allows the suitable combination of these two approaches to validate the structural solution. In this paper, we give examples of structure characterization by EXPO with the aim of suggesting a solution strategy for the application of reciprocal-space methods or real-space methods, or both.