>Leonid, I suggest you to try K4P2O7 - synchrotron data...
If you send me the data I may try.
OK.
K4P2O7 at room temperature is a good example for your horror museum of bad
things done in the SDPD world and which could have been so much better if
DDM was used.
This case belongs to the acentric class of problems. Acentricity leads to a
2 times more unfavourable (atomic coordinates)/data ratio than for centric
compounds. This is also the case for beta-Ba3AlF9 for which I can send the
original 1993 data, if you wish, and you may see if Al-F distances are
convincing without restraints using DDM (I obtained crazy Al-F distances in
the 1.65-1.97 A range, instead of 1.81+-0.04 A for usually regular AlF6
octahedra).
BTW, try to solve the structure before the Rietveld fif.
Best,
Armel
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Please do NOT attach files to the whole list <alan.he...@neutronoptics.com>
Send commands to <lists...@ill.fr> eg: HELP as the subject with no body text
The Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
