INTRODUCTION The results from a third structure determination by powder diffractometry (SDPD)...

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.

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.

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.

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, 2493- 2497. • 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.

REFERENCES

• Adil, K., Le Bail, A., Dujardin, G. & Maisonneuve V. (2007). Polyhedron 26, 2493- 2497. • 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.

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 : lachlan.cranswick@nrc.gc.caUniversité du Maine, Laboratoire des Oxydes et Fluorures, CNRS UMR 6010, Av. O. Messiaen, 72085 Le Mans, France. Email : Armel.Le_Bail@univ-lemans.fr

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 : lachlan.cranswick@nrc.gc.caUniversité du Maine, Laboratoire des Oxydes et Fluorures, CNRS UMR 6010, Av. O. Messiaen, 72085 Le Mans, France. Email : Armel.Le_Bail@univ-lemans.fr

Sample 1 : CaC4H4O6.4H2O

Sample 2 : La18W10O57

Conventional X-rays

Synchrotron Neutron