Data File A refinement applied to Data File B
The refined model obtained from Data File A was applied to the full data set contained in Data File B. The calculated parameters were unaltered, except for the background which was altered for the extended data range. The original Cheby II background produced a poor fit and so all the background points were cleared and the first Cheby II parameter given a value of 650. This first parameter was refined followed by separate refinement of the following five Cheby II parameters. The sixth background parameter could not be refined since it produced an unstable refinement.
Results
The final refinement window, obtained after 10 cycles of refinement, can be seen by clicking here. The refinement converged. The diffraction pattern calculated for the whole range of the data set B is shown in the following three images.
Comments
Examination of the images shows that there is a considerable discrepancy between the measured and calculated profiles at the higher angles. The difference plot illustrates this. As a result, Rwp was worse with this extended Data Set (20% compared with 5% when using Data File A). The calculated reflections are broad and thus not well resolved. Consequently, there are substantial differences in some of the measured and calculated intensities.
The use of the extended data range has highlighted the deficiencies in the model structure generated using the limited range Data File A.