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Using FOX for Ab Initio Structure Determination: PbSO4 tutorial
Prerequisites
First step: create your Crystal Structure
Second step: create the PowderPattern object (X-Ray)
Second step (bis): create the PowderPattern object (neutron)
- Just repeat the same steps (create a second PowderPattern object) (you can display both graphs at the same time), and choose neutron radiation with a wavelength of 1.909. A W parameter of 0.25, and a pseudo-Voigt witha Eta0=0.15 should be fine. Again, put a value of 0.25 in the max sin(theta)/lambda field.
Third step: create the Global Optimization object
Last step: export the crystal Structure
- You can export the atomic coordinates by going to the Crystal structure, and use the 'File'->'Save as text' menu. this will save a file with all atom fractionnal coordinates and occupancies. You should see that all atoms have a 'dynamical occupancy' of 0.5, which is due to the fact that they are all (except two oxygens) on a special position. The other two oxygens are in fact equivalent, as the distance table included in the output shows.
- You can also export to a CIF file using the same menu. Normally, atoms which are fully overlapping are taken care of so that only a single atom remains.
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