I wish to do a Rietveld refinement on my powder diffraction data using the GSAS+EXPGUI software package, where i have a freedom to chose the polarisation correction as a variable or can be fixed to a constant value. So instead of applying a polarisation correction during the data conversion in Fit2D, can i apply it in a later stage, ie during the Rietveld refinement?.
Irshad, if you are treating with powder X-Ray Diffraction, it is convenient to keep polarization factor in 0.5, to do this with EXPGUI go to Powder tab and put POLA = 0.5, IPOLA = 0, do not refine these parameters.
But my concern is that, i have a polarization correction factor that i am applying to the experimental data while converting it in Fit2D. now the experimental data is corrected against polarization correction. Whether i need to apply it again in the refinement?
You have not to do anything more with polarization factor after setting IPOLA = 0.5, when you start the refining the data, do not refine all the parameters ay once, apply Ray Young’s Refinement Strategy, that is, refine the parameters in this sequence:
*Scale factor
*Zero shift
*Linear background
*Lattice parameters
*More background
*Peak width
*Atom positions
*Preferred orientation
*Isotropic temperature factor
*U, V, and other profile parameters
*Anisotropic temperature factors
Repeat this sequence until the final result is acceptable.
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