The third Structure Determination by Powder Diffractometry Round Robin (SDPDRR-3
L.M.D. Cranswick and A. Le Bail
Canadian Neutron Beam Centre, National Research Council Canada, Building 459, Chalk River Laboratories, Chalk River ON, Canada, K0J 1J0. Email : [email protected]
Université du Maine, Laboratoire des Oxydes et Fluorures, CNRS UMR 6010, Av. O. Messiaen, 72085 Le Mans, France. Email : [email protected]
INTRODUCTION
The results from a third structure determination
by powder diffractometry (SDPD) round-robin are
summarized. From the 175 potential participants
having downloaded the powder data, 9 have
sent a total of 12 solutions (8 and 4 respectively
for samples 1 and 2, a calcium tartrate tetrahydrated
and a lanthanum tungstate). They used 7 different
computer programs for structure solution (ESPOIR,
EXPO, FOX, PSSP, SHELXS, SUPERFLIP, TOPAS),
applying either the Patterson or direct methods,
direct space methods, or the charge flipping
approach.
Sample 1 : CaC4H4O6.4H2O
Conventional X-rays
Sample 2 : La18W10O57
Synchrotron
Neutron
CONCLUSION
Solving a structure from powder data remains a hard job, an
order of magnitude harder than solving a problem with similar
complexity from single crystal data. Nevertheless, a few more
steps in the direction of routine were accomplished since the
two previous round-robins : that time, not only the computer
program developers were successful, but also some more
standard users. No result was obtained from crystal structure
prediction experts.
REFERENCES
• Adil, K., Le Bail, A., Dujardin, G. & Maisonneuve V. (2007). Polyhedron 26, 24932497.
• Chambrier M.H., Le Bail A. & Goutenoire F. (2008). http://www.crystallography.net/
• Clegg, W. & Teat, S.J. (2000). Acta Cryst. C56, 1343-1345.
• Le Bail A. (2003). COD1000005 - http://www.crystallography.net/
• Le Bail, A. & Cranswick, L.M.D. (2001). Commission on Powder Diffraction IUCr
Newsletter 25, 7-9.
• Le Bail, A. & Cranswick, L.M.D. (2003). Commission on Powder Diffraction IUCr
Newsletter 29, 31-34.
• Le Bail, A., Bazin, D., Daudon, M. & Maisonneuve, V. (2008).
http://www.crystallography.net/
• Zhu, J.H., Wu, H.X. & Le Bail, A. (1999). Solid State Science, 1, 55-62.