It should be noted that this structure was originally solved by manual interpretation of a 3D Patterson map generated by Shelx76.

Also refer to Armel LeBail's Tutorial on solving structures from powder data

• Original 1 at http://www.cristal.org/iniref/tutorial/indexa.html
• Original 2 at http://fluo.univ-lemans.fr:8001/iniref/tutorial/indexa.html
• CCP14 Web Mirror

This structure also solves with EXPO from the Sirware group [CCP14 Web Mirror]

As EXPO is an integrated system for solving crystal structures from powder data using direct methods, it would be advisable to try this software system first.

Starting Information

• A file of extracted intensities and HKLs in Shelx format as Fsqr's and the usual junk ESDs.

  It should be noted that WinGX is much friendlier if Fsquares are used over F's. This is because in the present version of WinGX, most of the setup of files automatically assumes Fsquares are going to be used. It is possible to use F's, but at present there is some tedious manual editing of files involved.

  The file is terminated using 0 (zeros). Following are the original 47 manually extracted intensities extracted using Philips PC-APD that were the basis of the original paper. Freely available options for doing this include XFIT, pkfit, Shadow, etc. The other common option is to use Le Bail extraction (and possibly Pawley extraction) to near automatically obtain the extracted intensities.

  As an example, Fullprof is a program that can output a shelx hkl file after Le Bail extraction (and during refinement), which can then get passed into a program such as Armel LeBail's OVERLAP program, which can convert to Fsquares, remove peaks that are excessively overlapped and fudge the ESDs so that Shelx actually will accept them. (The reason you might produce a Shelx file during refinement, is that you can then pass this into WinGX/Shelx/platon for facilities this software suite offers, including fourier, use of platon facilities for structure checking, easily placing hydrogens using Shelx or other software such as XHYDEX, etc.)
  Again, refer to the Le Bail extraction web page for information on software such as OVERLAP.

     2   0   0   106.1     1.0
     0   0   1   404.7     1.0
     2   0  -1   594.5     1.0
     2   0   1   921.3     1.0
     4   0   0   146.3     1.0
     4   0  -1   915.0     1.0
     1   1   0    64.1     1.0
     4   0   1   808.9     1.0
     3   1   0   532.2     1.0
     1   1  -1   532.5     1.0
     1   1   1   390.7     1.0
     0   0   2   448.3     1.0
     6   0   0   255.2     1.0
     2   0  -2   255.8     1.0
     2   0   2   220.0     1.0
     3   1  -1   294.4     1.0
     3   1   1   724.7     1.0
     6   0  -1   512.8     1.0
     6   0   1   206.7     1.0
     4   0  -2   377.6     1.0
     5   1   0   190.1     1.0
     4   0   2   355.2     1.0
     5   1  -1   342.2     1.0
     1   1  -2    74.1     1.0
     5   1   1   298.8     1.0
     1   1   2   299.2     1.0
     3   1  -2   503.1     1.0
     8   0   0   465.9     1.0
     3   1   2   682.2     1.0
     6   0  -2   966.4     1.0
     8   0  -1   119.8     1.0
     6   0   2   716.0     1.0
     7   1   0   506.7     1.0
     8   0   1   123.4     1.0
     0   0   3   123.7     1.0
     2   0  -3   126.3     1.0
     7   1  -1   606.3     1.0
     5   1  -2   606.9     1.0
     2   0   3   446.8     1.0
     7   1   1   692.5     1.0
     5   1   2    93.5     1.0
     4   0  -3   563.3     1.0
     0   2   0   851.1     1.0
     4   0   3   469.4     1.0
     8   0  -2   491.7     1.0
     2   2   0   101.5     1.0
     1   1  -3   650.7     1.0
     0   0   0     0.0     0.0
  

• Wavelength of radiation used.
  • 1.54056 Angstrom (Cu K-alpha)
• Space group
  • C 2/m (published in A 1 1 2/m to make it more comparable to related structures)
  • (It should be noted that if you have not determined the space group, WinGX can try using ABSEN authored by P McArdle to try and determine the spacegroup). In this particular case, the space group was determined manually. In the case of overlap problems, Le Bail fitting on various monoclinic spacegroups and using the overall profile fit as a guide is another possible method.

    The UNIT CELL was determined using ITO, though a tutorial on using the three main powder indexing programs using the CRYS2RUN system is available using this particular data.

• Chemical Composition/Formula:
  • Li 0.92, Ti 2.88, O6 (round this out to whole numbers for WinGX)
• Number of Formula Units per Unit Cell
  • Z = 2
• Unit Cell Dimensions:
  • a=14.0956(0.002) b=2.9524(0.002) c=4.8917(0.001) beta=92.1716(0.05)

Normally you would be doing the following:

• Setting up WinGX ready to try solving the structure
  (this involves using running the HKL file through ABSEN which can also try and determine the space group if you do not know this already)
• Using various programs inside WinGX to try and solve the structure
  • NB: All these programs do is suggest solutions, it is up to the user to find out which could be the correct one.
  • Trying to Solve with default DIRDIF Patty
  • Trying to Solve with default Shelxs Patterson Methods
  • Trying to Solve with default Shelxs Direct Methods
  • Trying to Solve with default Sir92 Direct Methods
  • Note that originally, manual interpretation of a Shelx 3D Patterson map - succeeded in originally solving the structure.
  • (Don't forget that the EXPO (sequel to Sirpow) Direct Methods program which is optimised for powder diffraction software from the Sirware group can also solve this particular problem)
• Examining the structure (bond angles/bond lengths; structure visualisation using cameron, struplo, ortep, platon, etc) to determine how "good" the "suggested" structure is.

Preparation Before Solving Data

• Start WinGX as you normally would or as shown in the introduction/starting out with WinGX and select the HKL file created using the Le Bail Extraction or Manual Fitting.

• Run either the slower method or express Model, PRELIM, AUTOSTART, to start off the confirmation/ determination of the space group and inputting of basic data. In this case, doing the AUTOSTART method.

• 

• When prompted, input the basic cell information, chemical formula. WinGX normally does quite an excellent job estimating Z. If it gets it wrong, input the correct Z. Then click on OK to continue.

• 

Try and Solve Using DIRDIF PATTY (Patterson Map and Fourier Cycling)

• To Try and solve using DIRDIF PATTY, go into the SOLVE, DIRDIF. Then AUTO, PATTY. When prompted, tell DIRDIF you have Fsquare's and let it roll. When completed, exit DIRDIF in a civilized fashion using the File, Exit option. (If you have already run Dirdif before this it is safest to do File, Full Tidy, exit then restart Dirdif. Dirdif has a tendency to remember what it has done previously which can be unhealthy under some cercumstances. Also, if the Dirdif menus are greyed out; exit, try reinitialising the *.ins and struc.cif file again using Model, Prelim, Initialise Files then run Dirdif again.)

• 

• The suggestion structure solution will be in the shelx format *.res file, which you can open using, REFINE, RES FILE. You can view the structure in Cameron to see if it visually makes sense; and you can save the *.res file as a Shelx *.ins file and refine on using the Refine menu option. This will give you a resulting Shelx LIST file.
  • Resulting View in Cameron using Include Cell; Pack, Cut; axis B
  • Note: Using a LIST 3 command during Shelx refinement would allow you to generate Fourier electron density contour Maps. Fobs Map using WinGX Fourier Map Generator and Viewer after Shelx refinement with LIST 3
  • To Some extent, you can use the WinGX, Model, Operations, Assemble Residues to assemble residues in a connected set. Though at present, this may not work all that well for some types of polymeric inorganic materials and minerals.

Try and Solve Using Shelx Patterson (Patterson Map and Fourier Cycling)

• To Try and solve using Shelx Patterson, go into the SOLVE, Shelx. Then when the SHELXS control panel appears, select the Shelx Patterson option.

• 

• 

• The suggestion structure solution will be in the shelx format *.res file, which you can open using, REFINE, RES FILE. You can view the structure in Cameron to see if it visually makes sense; and you can save the *.res file as a Shelx *.ins file and refine on using the Refine menu option. This will give you a resulting Shelx LIST file.
  • Resulting View in Cameron using Include Cell; Pack, Cut; axis B
  • Note: Using a LIST 3 command during Shelx refinement would allow you to generate Fourier electron density contour Maps. Fobs Map using WinGX Fourier Map Generator and Viewer after Shelx refinement with LIST 3.
  • To Some extent, you can use the WinGX, Model, Operations, Assemble Residues to assemble residues in a connected set. Though at present, this may not work all that well for some types of polymeric inorganic materials and minerals.