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SDPDRR-II ( Structure Determination by Powder Diffractometry Round Robin - 2 )

SDPDRR-II ( Structure Determination by Powder Diffractometry Round Robin - 2 ). WWW: http://www.cristal.org/sdpdrr2/ Started: Monday 9th September Part 1 (powder indexing): Start: Monday 9th September Finish: Sunday 13th October 8 samples 1 - 3 : Powder indexing and structure solution

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SDPDRR-II ( Structure Determination by Powder Diffractometry Round Robin - 2 )

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  1. SDPDRR-II (Structure Determination by Powder Diffractometry Round Robin - 2 ) • WWW: http://www.cristal.org/sdpdrr2/ • Started: Monday 9th September • Part 1 (powder indexing): • Start:Monday 9th September • Finish:Sunday 13th October • 8 samples • 1 - 3 :Powder indexing and structure solution • 4 - 8 :Powder Indexing only • > 100 downloads of the data (samples 1 to 3) Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk

  2. SDPDRR-II - Indexing Results • WWW: http://sdpd.univ-lemans.fr/sdpdrr2/results/ • 6 returns/100 downloads = 6% return rate Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk

  3. SDPDRR-II - Sample 1 • WWW: http://sdpd.univ-lemans.fr/sdpdrr2/results/ • Organisers: 10.323 7.395 8.535 90 91.29 90 • Reduced cell: 7.395 8.535 10.323 91.29 90.00 90.00 • P1: 10.318 7.393 8.527 90 91.3 90 • P2: 10.321 7.392 13.236 90 139.90 90 • P3: 10.322 14.787 8.529 90 91.35 90 • Reduced cell: 8.529 10.322 14.787 90.00 90.00 91.30 • P4: No solution • P5: 8.523 10.327 7.397 90 90 91.34 • P6: 8.525 7.394 13.230 90 128.748 90 Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk

  4. SDPDRR-II - Sample 2 • WWW: http://sdpd.univ-lemans.fr/sdpdrr2/results/ • Organisers: 11.239 8.194 19.943 90 106.727 90 • Reduced cell: 8.194 11.239 19.875 106.06 90.00 90.00 • P1: 19.880 8.195 11.242 90 106.06 90 • P2: 11.242 8.195 19.948 90 106.72 90 • P3: 19.878 8.193 11.240 90 106.06 90 • P4: 19.880 8.194 11.243 90 106.06 90 • P5: 11.244 19.882 8.196 90 90 106.06 • P6: 11.243 8.195 19.949 90 106.72 90 Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk

  5. SDPDRR-II - Sample 3 • WWW: http://sdpd.univ-lemans.fr/sdpdrr2/results/ • Organisers: 18.881 18.881 18.881 90 90 90 (vol 6734Å3) • P1: 13.349 13.349 9.439 90 90 90 (Tet - 1638Å3) • P2: 18.878 18.878 18.878 90 90 90 • P3: 13.354 13.354 9.442 90 90 90 (Tet - 1638Å3) • P4: No Solution • P5: 18.878 18.878 18.878 90 90 90 • P6: 18.88 18.88 18.88 90 90 90 Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk

  6. SDPDRR-II - Sample 3 Tetragonal or Cubic? • 2 participants (1 and 3) obtained the same tetragonal cell instead of the correct cubic. • Possibly due to default volume restrictions in the programs used(?) • What happens if you run LePage (via Chekcell) followed by a “parsimony of extra reflections” check on the tetragonal solution Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk

  7. SDPDRR-II - Sample 3: Tetragonal: 1 peak unmatched - 46 hkl’s (P42MC et al) to match 25 reflections Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk

  8. SDPDRR-II - Sample 3: Tetragonal: Running LePage shows a cubic cell (18.885Å) Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk

  9. SDPDRR-II - Sample 3: Visual inspection of cubic cell implies “bad”peak could still be an impurity Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk

  10. SDPDRR-II - Sample 3: Cubic: 37 hkl’s to match 25 reflections (I23 et al) (vs 46 hkl’s in tetragonal) Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk

  11. SDPDRR-II - Samples 4 to 8 • WWW: http://sdpd.univ-lemans.fr/sdpdrr2/results/ • Only one response - using the EFLECH/Index software of Joerg Bergmann (http://www.bgmn.de/related.html) • S4: none suggested • S5: 6.011 16.937 18.229 90 90 92.19 • S6: none suggested • S7: 4.417 11.479 17.126 77.87 85.09 82.67 • S8: 3.796 9.368 28.915 90 90 90 • Summary: Powder indexing is not easy and not routine! Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk

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