Powder pattern calculation from single crystal data

Powder pattern calculation from single crystal data
Hi

Kindly, I wanna know what the theoretical base of X-ray powder diffraction pattern calculation from single crystal data? and is the obtained pattern same as experimental powder pattern and if not same what the cause of difference? Thanks

Powder data are simply a projection of all single crystal data onto 1D x-axis, i.e. for each (hkl) you take the absolute Q(hkl) and put the respective intensity on the 1D axis at the point x=Q.

Powder data are simply a projection of all single crystal data onto 1D x-axis, i.e. for each (hkl) you take the absolute Q(hkl) and put the respective intensity on the 1D axis at the point x=Q.

Thanks alot for your answer, can you suggest textbook or paper to read about the theory and mathematical method which describe how the software convert single crystal diffraction data to powder pattern, i.e. 2Theta versus Intensity plot.

Best Regards

Thanks

Thanks alot for your answer, can you suggest textbook or paper to read about the theory and mathematical method which describe how the software convert single crystal diffraction data to powder pattern, i.e. 2Theta versus Intensity plot.

Best Regards

Well there are so many books on crystallography. Probably one of the best is by Vainshtein:

There is a lot of software for this. You can Google "powdercell", or www.oxfordcryosystems.com for a free copy of Crystallographica, or
"fullprof suite" or "gsas".

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Well there are so many books on crystallography. Probably one of the best is by Vainshtein:

There is a lot of software for this. You can Google "powdercell", or www.oxfordcryosystems.com for a free copy of Crystallographica, or
"fullprof suite" or "gsas".

Thanks for sending these nice books and software, but there is specific theoretical method deal with converting single crystal data to powder pattern plot, and I didn't found it in the general crystallography text books, as by Vainshtein, so do you know where I can found it and what is the keywords for it?

Thanks and sorry for confusion again

Last edited by a moderator:
Thanks for sending these nice books and software, but there is specific theoretical method deal with converting single crystal data to powder pattern plot, and I didn't found it in the general crystallography text books, as by Vainshtein, so do you know where I can found it and what is the keywords for it?

Thanks and sorry for confusion again

This type of plot is possible in 'Winplotr' (from FullProf). Actually in general the powder pattern will depend on the geometry of XRD experiment. In short, you should use your .hkl-file with intensities and ask Fullprof to calculate the diffracton _powder_ pattern for your powder resolution parameters that are also specified in the input file in Le Bail (powder matching) mode. To make a really true conversion one needs a collection of reflections within Ewald sphere (symmetric in 4pi).

A big difference in powder (PD) and SC (SCD) diffraction experiment is that in the PD you have a profile I(2\theta), whereas in SCD you have already integrated peaks.

The conversion of just integrated intensities is extremely straightforward. For each reflection you calculate \theta and add the intensity to I(2\theta). You should allow some tolerance in 2\theta, because you are dealing with experimental data having some errorbars. There is also correction for Lorenz factor (LF). If your original SCD data were already corrected for LF, then you multiply I(2\theta) by 1/[sin(\theta)*sin(2\theta)]. We assume some standard Bragg-Brentano PD. This way you will get the integrated intensities, but not the profile, which is dependent on the resolution parameters.

can anyone you tell me how to get the miller indices and cell parameters from powder XRD pattern

thank you can you suggest any formula for calculating the cell parameters with 'd' and 2theata

hai
can you suggest the formula for finding the miller indices from powder xrd pattern with d and 2 theta values.

Best regards

Gokul43201
Staff Emeritus