Indexing

• Select a cell from the list of cells produced by TRCELL. Normally the top one should be tried first.

  
  
           select cell 1
  
  

• Give (reasonable starting) values for wavelength, resolution and the volume:

  
  
           wavelength 0.6 2.0
           resolution 1.0
           volume 13073.2
  
  

• Index the pattern based on the selected cell and crystal orientation and judge if the predicted pattern matches the observed pattern well enough.

  
  
           run indxpat
  
  

  Double click on the update pred/remove pred button of xdisp to see the predicted diffraction pattern. If the (soft) limits , , and volume appear to be acceptable (number of spots predicted is of the same order as the number of spots observed, and the distribution of the predicted and observed spots over the plate is comparable), you can judge from the general pattern (especially around the ``main conics'') and the root-mean-square difference between the predicted and observed spot positions, in combination with the number of spots indexed, if the correct cell was chosen or not.
• Repeat the previous step for other cells from the list produced by TRCELL as well, in order to make sure that the correct cell was found:

  
  
           select cell 2
           run indxpat
  
  

  Check again visually and quantitatively (by means of the root-mean-square value and number of spots indexed) if the selected cell is the correct one or not.
• If none of the cells gave a satisfactory match between the predicted and observed pattern, check the soft limits in the way described in the next section. If these limits seem fine, rerun TRCELL.