Extracting integrated intensities from powder diffraction patterns

This chapter deals with the theoretical aspects of extracting integrated intensities from a powder diffraction pattern and with the ancillary issue of space group determination. Two principal methods are discussed: the iterative Le Bail method and the constrained linear least-squares approach of Pawley. The origins and mathematical basis of both methods are discussed and examples given to illustrate their performance on particular problems. The problems that occur in dealing with reflections that are strongly overlapping are considered and some methods for overcoming them suggested. A probabilistic basis for space group selection, based upon intensities extracted from a Pawley fit, is also given and illustrated with examples.