Hello All,

I calculated structure factors from a pdb with sfall and then used those to generate a simulated powder diffraction pattern with xprep. To compare, I also plotted the intensities (F x F*) straight from the mtz file. Attached are the two patterns as png files (sfall only: "mtz.png"; sfall→xprep: "xprep.png").

Does anyone know what xprep is doing to the low resolution data (> ~20 Å)? It seems to be clipped. The xprep manual[1] says nothing about simulated powder diffraction.  The patterns < ~20 Å are more-or-less comparable (although you can't tell from the pictures).

James


[1] http://shelx.uni-ac.gwdg.de/tutorial/english/xprep.htm