The Institute of Pharmaceutical Innovation

A simulated annealing approach for crystal structure solution

A Simulated Annealing Approach for Crystal Structure Solution from Powder Diffraction Data

G. E. Engel, S. Wilke, K.D.M. Harris, B.M. Kariuki, S. Ahn, F.J.J. Leusen; M.A. Neumann

We discuss fundamentals and applications of the program “Powder Solve” that has been developed to solve crystal structures directly from powder diffraction data. The program uses a combination of simulated annealing and rigid-body Rietveld refinement techniques to find the trial structure giving maximal agreement between calculated and experimental powder diffraction data (assessed using the profile R-factor R-wp). Two examples are highlighted to demonstrate the application of Powder Solve for molecular crystals defined by up to 18 variable degrees of freedom.