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:
At this point we have already defined the space group and
wish to do a Face Index Absorption Correction. This assumes you
have an HKL file with direction cosines.
Run WinGX to bring up the following Menu Bar
Click on Absorb, Numerical, Analytical menu option to enter the absorption correction option.
If WinGX detects an existing faces.def file, which has the indices and distance information, (implying you this is not the first absorption correction you have attempted on this sample) it will query whether you want to use this.
The faces.def file has the following format (distances in mm)
CELL 13.385 7.422 15.133 90.00 107.70 90.00 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
If you already have kosher a faces.def file to use, just used this, other wise refer to XtalView and Entering Faces for the First Time which will show you how to enter the faces via the WinGX GUI menu.
If using an existing faces.def file, one thing you may like to
do is go into XtalView and just check that the crystal does
look like the original one mounted on the diffractometer. Cancel out
of the absorption correction and run Absorp, Numerical, Xtal View
and examine what the crystal looks like.
After exiting XtalView, go back to the procedure and tell WinGX you do want to use the existing faces.def file.
WinGX will leave a Platon Dialog Window where you can check a summary.
After removing the Platon summary screen, WinGX will leave a confirmation dialog box stating how it has created a new HKL file with the absorption corrected intensities.
The thorough Platon output is in the absorb.lst file where you can check the exact corrections Platon has performed on your HKL data. This can be accessed easily via the top menu under Analyse, Open List File, ABSORP
H K L F**2 Sig(F**2) Transmission Volume (mm3) 0 0 -20 845.92 30.71 0.43737 0.00628806759 0 2 -19 110.40 15.49 0.42736 0.00628806759 -1 1 -19 192.97 18.52 0.43188 0.00628806759 -4 0 -18 397.35 18.86 0.42851 0.00628806759
The new Shelx ready absorption corrected
hkl file is titled analytcl.hkl. You can rename you cosine
based hkl file with direction cosines to a backup file then copy the
analytcl.hkl file to be the project hkl file that will be used for
solution and/or refinement. Though for refinement, WinGX can
detect what types of HKL files you have allowing you to vary
the type of absorption corrected HKL files you are using so you
can explore the effect of absorption on the structure.