Rietveld refinement guidelines

A set of general guidelines for structure refinement using the Rietveld (wh ole-profile) method has been formulated by the International Union of Cryst allography Commission on Powder Diffraction. The practical rather than the theoretical aspects of each step in a typical Rietveld refinement are discu ssed with a view to guiding newcomers in the field. The focus is on X-ray p owder diffraction data collected on a laboratory instrument, but features s pecific to data from neutron (both constant-wavelength and time-of-flight) and synchrotron radiation sources are also addressed. The topics covered in clude (i) data collection, (ii) background contribution, (iii) peak-shape f unction, (iv) refinement of profile parameters, (v) Fourier analysis with p owder diffraction data, (vi) refinement of structural parameters, (vii) use of geometric restraints, (viii) calculation of e.s.d.'s, (ix) interpretati on of R values and (x) some common problems and possible solutions.