[RMCProfile-users] G(r) from X-ray diffraction data

[Clemens Prescher]

Hi there,

i have problems figuring out how X-ray derived PDF should be correctly
inputted into RMCProfile.

On page 157 in the RMCProfile manual it is written that the X-ray G(r)
needs to be normalised so that it is scaled from 0 to 1. This is exactly
the format i have. However, if I init my calculation and plot the "PDFs of
rmc fit" using rmcplot it has an offset (please see the attached figure "
gr_without_offset.ps")

It is clear, that the RMC fit is actually normalized to 0 when going into
infinity.

I thought, this might just a result by subtracting 1 from the previously 0
to 1 normalized G(r). But after several iterations using an offset of -1 it
became clear that low part is not normlized to -1. (see the
"gr_with_offset" figure attached).

In the manual it is also written that G(r) goes from -(sum c_j b_j)² to 0.
But for X-ray this does not make sense due to q-dependent form factors...

Can you please explain me how i should transform my data?

Best wishes,
Clemens
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