Simulated Powder Pattern from HKL-Iobs

Simulated Powder Pattern

A Powder pattern is generated for the supplied reflection file containing F(obs)**2 data along with the cell and symmetry info in .res, .cif or .spf format.

Example: use a name.res & associated name.hkl for the structure of interest.

I(obs) data are calculated from F(obs) or F(obs)**2 data and include the reverse application of the Lp-correction factors.

The reflection data are averaged first according to the Laue symmetry associated with the space group symmetry as supplied. The number of missing data is reported (commonly low order reflections, often not in the data set for various reasons - e.g. behind the beamstop etc). Subsequently, the data set is expanded to a halfsphere of reflections (recorded in a file with extension .hkp).

A powder file is generated in CPI format on a file with extension .cpi

Notes:

1. See for a tutorial by Lachlan Cranswick.

2. The Lp-correction applied is that for the Debije-Scherrer technique.

3. The reflection profiles are Lorentzian: L(x) = I(obs) / (1 + A * x**2).

4. Given a file name.fcf reflection CIF, no additional file will be needed: invoke platon name.fcf.

5. Given a name.cif and name.fcf a powder pattern is generated by invoking platon -P name.cif.

6. Given a name.ins and name.hkl a powder pattern is generated by invoking platon -P name.ins.

The optional parameter ttm can be used to select the twotheta range:

1 = 20, 2 = 40, 3 = 60, 4 = 80 and 5 = 180 degrees.

platon -P name.res - Direct path to I(obs) powder pattern on display.

platon -o -P name.ins - Will produce an I(obs) powder pattern as a postscript file and a .cpi SIETRONICS style file.

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