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Tutorials and Examples

Louis Farrugia's WinGX Single Crystal Suite

Starting out - Setting up and Confirming the Space Group

The CCP14 Homepage is at http://www.ccp14.ac.uk

[Tutorials page] | [WinGX Tutorial Index]

This example uses the raw hkl data used to determine the crystal structure of Cs2TiSi6O15 as published in I.E. Grey, R.S. Roth, M.L. Balmer, Journal of Solid State Chemistry, 131, 38-42 (1997).

The starting information that is normally known before starting WinGX is:

  • Wavelength of radiation used.
    • 0.71073 Angstrom (Mo K-alpha)
  • Space group
    • C2/c
  • Unit Cell Dimensions:
    • a=13.3860(0.002) b=7.4230(0.002) c=15.1340(0.001) beta=107.710(0.05)
  • Cell contents/Composition:
    • Cs2TiSi6O15
    • Z (number of formula units in the cell) =4 (WinGX can try to estimate Z)
  • 2-theta scan range
    • 2 to 30
  • Colour and habit of crystals
    • colorless, transparent tabular-shaped crystals.
  • Crystal size
    • 0.24mm x 0.24mm x 0.10mm
  • Absorption Correction: Analytical using crystal faces (distances in mm)
    FACE      2   0   0   0.12000
    FACE     -2   0   0   0.12000
    FACE      0   2   0   0.12000
    FACE      0  -2   0   0.12000
    FACE      0   0   2   0.05200
    FACE      0   0  -2   0.05200
    


Run WinGX to bring up the following Menu Bar

Starting Menu Bar

From the menu, select Files, Job Paths, Move Working Directory and select the hkl file from which you are going to work with.

Selecting file to use

A Window will pop up that No (shelx) INS file was found for the Structure. This is OK as the Shelx INS file has not been created yet.

Message stating there is no ins file

A summary window will then appear which has no information in it yet.

Model summary window


(In the latest WinGX 1.62, running Model, PRELIM, AUTOSTART, will automatically try and do everything for you (prompting for confirmation of suggested space group and cell contents, etc) then automatically try and solve the structure in Shelxs. The following is done the slower way but gives more checking information)

To Model, PRELIM, E-statistics, to start off an initial look at the HKL data

E-stats Menu Option

If you have absorption corrected your data by various methods (i.e., gaussian, analytical, etc). Select the dataset you consider most appropriate.

Auto-start menu option

When prompted, input the basic cell information, and Molecular Formula. Then select Estimate Z to have WinGX estimate the number of Formula units in the cell. (WinGX does quite an excellent job estimating Z. However, if is estimates incorrectly, it is up to the user to correct it).

Crystal Data Prompt Box

WinGX will then look at the HKL data then output a number of graphs for you to evalulate by eye.

E-stats graphs

E-stats graphs

WinGX will then give you a warning that E-stats are just a guide.

WinGX E-stats warning


Now we want to determine the spacegroup. Thus via the menu, select Model, PRELIM, Assign Spacegroup.

Model, PRELIM, Assign Spacegroup menu

WinGX will then run Patrick McArdle's ABSEN software to try and suggest the most likely spacegroups. WinGX will bring up a screen prompting you to confirm or change the cell constants and cell type

WinGX prompting to confirm cell constants and cell type

WinGX will then recommend a space group (in this case, correctly C 2/c. You can over-ride this if you want and either directly enter or browse the list of possible spacegroups.

Suggesting of a spacegroup

Click OK to terminate this dialog box so you can continue on to via the Model, PRELIM menu system to create the starting Shelx and CIF files.


Now we want to initialise the Shelx INS and CIF files so we can then make a start on solving the structure. Thus via the menu, select Model, PRELIM, Initiliase Files.

Model, PRELIM, Initiliase Files menu

WinGX will bring up a GUI window to input the extra information it needs to create the starting Shelx file and CIF files. Click on whether you are using F's or Fsquares, temperature of the data collection, X-rays Neutrons and the Wavelength being used.

UNIT CELL Initilise Structure file Window

Then select the Crystal Information tab and input the crystal colour and dimensions (and redo Z if you wish).

Physical Properties Initilise Structure file Window

Fill in as much software information as you can at this point.

Programs Used Initilise Structure file Window

Press OK and WinGX should then prompt with a message stating.

INS and CIF file created message.


You may now continue on to either do various types of absorption correction or try and solve the structure using the available software, Shelxs, Sir or DIRDIF.


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