Obtaining Peak Positions from the powder diffraction pattern

Converting the XFIT file into Crysfire format

Crysfire can import the following peak listing format.

  EV = Bruker Socabim EVA format (EVA2Crys: Arie van der Lee)
  UD = Philips UDI format        (UDI2Crys: Robin Shirley)
  WF = WinFit format             (WF2Crys:  Robin Shirley)
  XF = XFit format               (XF2Crys:  Robin Shirley)

The following assumes you have already created a Crysfire CDT file. Available, example tutorials for importing data into Crysfire are:

• Inputting a list of peaks / observations into Crysfire

• Importing an XFIT Peak Listing into Crysfire and creating a CDT file (Winfit, Philips and Bruker files can also be imported into Crysfire)

Rescaling the peak list data

As per the above screen dump, Crysfire has recommended using a rescaling factor of 0.5. Bear in mind that you might have to play with this and try a variety of rescaling values.

To rescale the data, type RS. Choose a rescale factor that you would expect the cell to then move into the 500 - 1500 A**3 range. At first, try the value recommended by Crysfire (in this case 0.5). Remember this value as you will need it to unscale the data after running all the indexing programs.

After rescaling, Crysfire will prompt to save the file with an R2 appended to the filename so as to distinguish this from the starting CDT file.

Now Run all the relevant Crysfire based indexing programs as per the Crysfire Basic tutorial (via the IN (Indexing) command)

• Taup
• Dicvol - high symmetry
• ITO
• Fjzn
• Treor
• Kohl
• Dicvol - low symmetry
• Lzon

Analyse your scaled results using MMAP

Due to the MMAP defaults not liking very large cells, it is best to run MMAP on the "scaled" data before unscaling the summary file.

Too evalute solutions with MMAP, first make sure you have the relevant CDT file loaded into memory (using the LO command).

Then use the Load Cell command (LC) to load a trial cell into Crysfire's memory. The following screen dump gives the type of prompt you will encounter. (remember that you are using scaled results)

Tell Crysfire you wish to load a cell from the Crysfire summary file on which you will be given the Summary file list.

Select Cell the top FOM solution by typing 1. After accepting this and the various Crysfire information, you will be prompted to Display the 3 principal M1-map sections for this cell. Type Y for Yes.

Following is a MMAP Merit Map from solution 3 (a cubic cell).

Unscaling the results via the MS menu (Modify SUM files)

After you have run all the relevant indexing programs, you now need to unscale the results in the summary file via the MS (Modify SUM files) menu system.

When prompted, give the name of the Crysfire run you wish to unscale (in this example, crys1r2, the output file (try adding us to the filename - crys1), and the scaling factor you used (0.5 for this example). When prompted, you may like to give a file description making it obvious that this data has been scaled, then unscaled.

Analyse your unscaled results

Now try Chekcell

Now might be a good time to pass the results over to the Chekcell graphical indexing helper tool by Jean Laugier and Bernard Bochu and see which might be the best solution.

• Tutorials: http://www.ccp14.ac.uk/tutorial/lmgp/index.html#chekcell
• Download: [CCP14 UK Web Mirror] | [Canadian CCP14 Mirror] | [US CCP14 Mirror] | [Australian CCP14 Mirror]
• Bleeding Edge beta test versions of Chekcell can be obtained via the "bleeding_edge_beta_versions" subdirectory in the above download area.

Make sure you peruse the following tutorial: Using Ton Spek's Lepage within Chekcell to find super-cells and better trial cell solutions

Crysfire Log file

Crysfire creates a Log file of all the major functions you run, opening the relevant *.LOG file will display what you did.