1. Re-stating the obvious: To solve structures from powder diffraction, first they must be indexed! Lachlan M. D. Cranswick CCP14 (Collaborative Computation Project No 14 for Single Crystal and Powder Diffraction) Department of Crystallography; Birkbeck College, University of London, Malet Street, Bloomsbury, London, WC1E 7HX, UK. E-mail: l.m.d.cranswick@dl.ac.uk WWW: http://www.ccp14.ac.uk

2. Based on a co-authored presentation at the ACA 2002 conference in San- Antonio, Texas, USA Lachlan M. D. Cranswick CCP14 (Collaborative Computation Project No 14 for Single Crystal and Powder Diffraction) Department of Crystallography; Birkbeck College, University of London, Malet Street, Bloomsbury, London, WC1E 7HX, UK. E-mail: l.m.d.cranswick@dl.ac.uk WWW: http://www.ccp14.ac.uk Robin Shirley School of Human Sciences University of Surrey Guildford, Surrey, GU2 7XH, U.K. Tel: (+44) 01483 686864 Fax: (+44) 01483 259553 E-mail: R.Shirley@surrey.ac.uk

3. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 3 Talk Aims Some history of Indexing of Powder Diffraction Data Peak finding and peak profiling software Fundamental Parameters Peak Fitting Available powder indexing software and indexing suites Crysfire in action Chekcell in action MCMaille by Armel Le Bail (released Sep 2002) Possibilities for the future and conclusion

4. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 4 Some History of Powder Indexing First published manual powder indexing method: –Runge, C. (1917), "Die Bestimmung eines Kristallsystems durch Rontgenstrahlen", Physik. Z., 18, 509-515. Candidates for first published computer based powder indexing –Haendler, H. M. & Cooney, W. A. (1963), "Computer Determination of Unit-Cell from Powder-Diffraction Data", Acta Cryst., 16, 1243-1248. –Lefker, R. (1964), "Indexing of tetragonal and hexagonal X-ray powder photographs with the aid of a small computer", Anal. Chem., 36, 332-334.

5. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 5 Some History of Powder Indexing - 2 Candidates for first published publicly available powder-indexing program –Haendler, H. M. & Cooney, W. A. (1963), "Computer Determination of Unit-Cell from Powder-Diffraction Data", Acta Cryst., 16, 1243-1248. –Lefker, R. (1964), "Indexing of tetragonal and hexagonal X-ray powder photographs with the aid of a small computer", Anal. Chem., 36, 332-334. –Werner, P.-E. (1964), "Trial and error computer methods for the indexing of unknown powder patterns", Z. Krist., 120, 375-387. –Hoff, W. D. & Kitchingman, W. J. (1966), "Computer indexing of x-ray powder patterns from crystals of unknown structures", J. Sci. Instrum., 43, 952-953.

6. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 6 Some History of Powder Indexing - 3 Candidates for first publically available general indexing program –Ishida, T & Watanabe, Y. (1967), "Probability Computer Method of Determining the Lattice Parameters from Powder Diffraction Data", J. Phys. Soc. Japan, 23, 556-565. –Roof, R. B. (1968), "INDX: A Computer Program to Aid in the Indexing of X-Ray Powder Patterns of Crystal Structures of Unknown Symmetry", Los Alamos Laboratory, University of California, Report LA-3920. –Taupin, D. (1968), "Une Methode Generale pour l'Indexation des Diagrammes de Poudres", J. Appl. Cryst., 1, 178-181. –Visser, J. W. (1969), "A Fully Automatic Program for Finding the Unit Cell from Powder Data", J. Appl. Cryst., 2, 89-95.

7. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 7 Checking Sample Purity Powder indexing requires line-position data of the highest available quality An important aspect of this is purity, since indexing programs don’t like to struggle with impurity lines, and several will not accept them at all. Some suggestions from Robin for checking sample purity: –Optical (polarising) microscope –Density analysis in a gradient column –Electron microscopy and diffraction of selected crystallites –And, if time permits, see whether properties are changing with time

8. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 8 Peak Profiling Software For Overall Summary of available peak profiling software refer to: http://www.ccp14.ac.uk/solution/peakprofiling/ Some of the available freeware includes: –CMPR –DRXWin –EFLECH –GPLSFT –pearson.xls –Rawplot (with GSAS) –SHADOW –Powder v2.00 –PowderX –Winfit –Winplotr (with Fullprof) –XFIT

9. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 9 Empirical peak fitting : Some tricks may be required for stability and reasonable results Peaks over small ranges may have to be linked to have the same shape and width Usually fit small ranges of data - groups of peaks Might have to fit large and medium peaks first, followed by trace peaks

10. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 10 Peak Profiling: high accuracy peak positions using Fundamental Parameters peak profiling Example of Fundamental parameters (convoluting in the geometry elements of the diffractometer) that can provide accurate peak positions as though your sample was being run on an “ideal” diffractometer. Tutorial at: –http://www.ccp14.ac.uk/tutorial/xfit-95/fun1.htm Available Fundamental Parameters Peak Profiling and Rietveld software: XFIT (no longer maintained) –http://www.ccp14.ac.uk/tutorial/xfit-95/xfit.htm Topas (Commercial - sequel to XFIT) –http://www.bruker.com BGMN (Commercial - academic demonstration version is freely downloadable) –http://www.bgmn.de EFLECH/Index freeware from BGMN website –http://www.bgmn.de/related.html

11. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 11 XFIT Fundamental Parameters Peak Profiling mode : fit to a low angle peak on a Bragg-Brentano diffractometer

12. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 12 Powder Indexing FOM Results XFIT Fundamental Parameters peak profiling compared to empirical Peak Fitting

13. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 13 Powder Indexing - indexing programs Overall Summary of available powder indexing software refer to: http://www.ccp14.ac.uk/solution/indexing/ Powder Indexing: –Classic (widely used): Ito, Dicvol, Treor –High symmetry (exhaustive): Taup (=Powder), Dicvol –Other powerful (general symmetry): Lzon, Kohl (=TMO), Fjzn –Dominant-zone cases: Lzon, Losh, Mmap –Semi-automatic (via SIW basis set): Losh, Mmap –Fundamental parameters & covariance matrix: EFLECH/Index –Incommensurate, etc: Supercell –Monte Carlo / Random search: EFLECH/Index, McMaille –Others (better with some user guidance): Scanix, Autox

14. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 14 Powder Indexing - indexing suites Overall Summary of available powder indexing software refer to: http://www.ccp14.ac.uk/solution/indexing/ Integrated Suites: –Crysfire –Powder v2.00 –PowderX –PROSZKI –WinPlotr and after primary indexing: –Chekcell

15. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 15 Powder Indexing - specialist programs Supercel is a specialised indexing program by Juan Rodriguez-Carvajal for tackling incommensurate cells and super/sub-cell relationships. (available within Winplotr/Fullprof) Web: http://www-llb.cea.fr/winplotr/winplotr.htm FTP: ftp://bali.saclay.cea.fr/pub/divers/fullprof.2k/

16. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 16 Powder Indexing - specialist programs McMaille reconstitutes a peak listing into a full profile and performs monte carlo based searching for good cells. Because it is Monte Carlo based it can be very slow, but due to it being whole profile, can be insensitive to trace impurity peaks. Web: http://www.cristal.org/McMaille/

17. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 17 Powder Indexing - Using PowderX –by Cheng Dong –http://www.ccp14.ac.uk/tutorial/powderx/ Peak finding Links to Treor

18. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 18 Powder Indexing - Using Winplotr –by Juan Rodriguez-Carvajal and T. Roisnel http://www- llb.cea.fr/fullweb/powder.htm Peak finding / profiling Links to –WinTreor, –Windicvol, –Winito and –supercell

19. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 19 Powder Indexing - the Crysfire suite (1) –by Robin Shirley (+ many contributing authors) –http://www.ccp14.ac.uk/tutorial/crys/ Intelligent defaults for control-parameters when launching each indexing program Data rescaling for tackling high-volume cells from macromolecular samples and zeolites Integrated under a common interface for use by non- specialists

20. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 20 Powder Indexing - the Crysfire suite (2) Principal Contributors: Franz Kohlbeck (Kohl [=TMO]) Daniel Louër (Dicvol, Lzon, Losh) Robin Shirley (Overall + Mmap, Lzon, Losh, Fjzn, etc) Ton Spek & A.Meetsma (Lepage) Daniel Taupin (Taup [=Powder]) Jan Visser (Ito, Fjzn, Lzon, etc) Per-Eric Werner (Treor)

21. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 21 Powder Indexing - the Crysfire suite (3) Crysfire 2000: 8 different indexing programs (Ito, Dicvol, Treor, Taup, Kohl, Lzon, Fjzn, Losh) It’s good to have a wide variety of methods available: – to cater for different types of problem – to give a feel for the range of solutions out there – and see which ones turn up repeatedly using different methods, either identically or as derivative cells

22. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 22 New Release - Crysfire 2002 August 2002 Now 9 indexing programs: Ito, Dicvol, Treor, Taup, Kohl, Lzon, Fjzn, Losh, Mmap New features: Mmap for exploring solution-space and evaluating trial cells Le Page/Niggli reduced-cell summary Greater ease of use, especially for first-time users Better resilience, especially under the Windows/NT family (master program totally rewritten)

23. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 23 Why bother running more than one powder indexing program? Maximize the possibility of indexing unknowns by taking advantage of different algorithms and different program implementations.

24. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 24 Powder Indexing - Routine Crysfire Example Run crysfire (giving the following screen)

25. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 25 Powder Indexing - Routine Crysfire Example Importing an XFIT peak file using the IM (Import command)

26. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 26 Powder Indexing - Routine Crysfire Example “lo” to load a CDT file estimate of expected unit cell volume is given

27. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 27 Powder Indexing - Routine Crysfire Example “in” to target an indexing program

28. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 28 Powder Indexing - Routine Crysfire Example target ITO with defaults

29. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 29 Powder Indexing - Routine Crysfire Example ITO runs

30. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 30 Powder Indexing - Routine Crysfire Example After Ito completes, press enter to see output file

31. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 31 Powder Indexing - Routine Crysfire Example Then “enter” again to see “one solution per line” summary

32. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 32 Powder Indexing - Routine Crysfire Example “Enter” again to see Le Page summary of reduced cells

33. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 33 Powder Indexing - Routine Crysfire Example Repeat the sequence to run the remaining relevant indexing programs. Recommended sequence is actually: –Taup, Dicvol high sym, Ito, FJZN, Treor, Kohl, Dicvol low sym, Lzon –in to select and launch an indexing program –look at the output file –look at the summary file –look at the Le Page summary file of reduced cells –repeat

34. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 34 Powder Indexing - Routine Crysfire Example Finally: the complete summary file - 3332 trial solutions

35. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 35 Powder Indexing - Routine Crysfire Example Complete Le Page summary file of reduced cells - 3332 trial solutions

36. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 36 Crysfire Self Calibration Bragg-Bretano Data Sometimes it’s hard to be sure how far the beam is penetrating into the sample, giving an unknown sample-displacement error This can be addressed by trying self-calibration (SC) –If indexing the uncorrected data has failed, try SC –Select T (for specimen-displacement correction ratio) –A list of candidates for T will be displayed, based on 1st/2nd-order line pairs –If a particular ratio comes up several times and looks plausible, adopt it –Save it (SA) in Crysfire format under a new name, so that it can be reloaded –Do another cycle of indexing runs, this time with the “corrected” data

37. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 37 Crysfire Self Calibration Example Self calibration output of an organometallic sample in histogram format

38. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 38 Crysfire Rescaling Most indexing program have evolved using a range of data with solutions between 500 and 1500 If you have cells outside this range, many indexing programs can fail A possible solution to still index large cells it to rescale the data by changing the wavelength

39. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 39 Crysfire Re-scaling Protein Data (from Bob von Dreele) Input for RAWPLOT: (1.15006 Å) 1.168100 1.656041 1.852174 1.918506 2.089703 2.345176 2.536523 2.623267 2.916919 2.992132 3.144491 3.319995 3.419907 3.458655 3.522905 3.564255 3.660448 3.712916 3.838720 3.933115 4.098415 4.151839 4.187484 4.234265 Lysozyme – single peak fits for 24 reflections : Rescale factor = 0.1 Rescaled cell = a of ~7.9Å and c of ~3.8Å Unscaled cell = a of ~79Å and c of ~38Å

40. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 40 Crysfire Rescaling example Inorganic - on opening : Crysfire suggests rescaling

41. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 41 Ignoring the rescaling suggestion No obvious solutions

42. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 42 RS is the Rescale Command Crysfire will automatically change the filename and title

43. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 43 After running the indexing programs: MS, then U to unscale the summary file

44. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 44 Indexing using the suggested rescaling of 0.5 An obvious cubic (23.923 A) solution found by Taup

45. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 45 Chekcell: Interpreting Crysfire Summary Files: Powder Indexing and Spacegroup Assignment Crysfire interlinks with Chekcell for Windows (part of the LMGP suite for Windows by Jean Laugier and Bernard Bochu). Chekcell provides a graphical interface for manually and automatically suggesting a best cell/spacegroup combination using both FOM and algorithms relating to parsimony of superfluous HKLs. http://www.ccp14.ac.uk/tutorial/lmgp/

46. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 46 Chekcell : easy to see non-matching or impurity peaks

47. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 47 Chekcell : automatic cell and spacegroup searching can trudge through a single selected unitcell; or over 1000s of trial cells looking for the best cell and spacegroup combination based on parsimony of extra reflections criteria.

48. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 48 Chekcell: “integration” of Ton Spek and A. Meetsma’s Le Page (Crysfire 2001 now also provides a reduced-cell summary) Obtaining the Reduced Cell –which in the past many powder indexing programs have not determined either reliably or at all –Refer: "'Reduced Cells', M.J. Buerger, (Zeitschift fur Kristallographie, BD 109, S. 42-60 (1957)” –Crysfire 2001 gives a LePage overview Chekcell displays a fuller analysis Efficient Sub-cell and super-cell searching, then easy reviewing of newly derived cells within the Chekcell interface

49. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 49 Chekcell: GUI Cell transformation Easily transform cells and test them withing Chekcell Knows about common transformations Can manually look at sub-cells and super-cells

50. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 50 Chekcell: Density / Z/ Mol. Vol explorer Easily explore values of Z, density and estimated molecular volume - comparing with your found trial cells.

51. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 51 Chekcell: example of it running Load the raw diffraction data

52. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 52 Chekcell: example of it running Load the peak position file

53. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 53 Chekcell: example of it running Load the Crysfire summary file

54. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 54 Chekcell: example of it running Use the tools to evaluate the trial cells

55. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 55 Crysfire / Chekcell: indexing powder Protein data Using the “Lepage” feature in Chekcell Can find the correct rhombohedral cell as published in: R. B. Von Dreele, P. W. Stephens, G. D. Smith and R. H. Blessing, "The first protein crystal structure determined from high- resolution X-ray powder diffraction data: a variant of T3R3 human insulin-zinc complex produced by grinding", Acta Cryst. (2000). D56, 1549-1553.

56. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 56 Crysfire / Chekcell: indexing powder Protein data Even on rescaled data, if Crysfire and the various indexing programs do not find the “true cell”, Chekcell and possibly can find a derivative cell which LePage (combined with Chekcell’s “parsimony and superflous reflections” criteria), can find the true cell. In the case of reindexing of the protein data: – Crysfire and Dicvol finds 73.2645 70.5256 40.7430 90.000 90.000 90.000 Orthorhomic –P222 or PMM2 or PMMM : 157 hkls to match 41 reflections –LePage followed by Chekcell “parsimony check” then finds: 81.449 81.449 73.265 90.000 90.000 120.00 Hexagonal setting 52.988 52.988 52.988 100.45 100.45 100.45 Rhombohedral –R-3 or R3 etc : 60 hkls to match 41 reflections

57. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 57 MMAP Mmap explores sections of solution-space (e.g. sections with varying alpha* and beta*, holding the other 4 parameters constant) The results are displayed as a map, with the high-ground colored It lists all the peaks in the map and refines them - each is a trial solution So it can act as an indexing program in its own right (taking the basis set containing the first 4 constants from Lzon’s output) This offers another way to search for trial cells Use the new “LC” (Load a trial cell from the Crysfire summary file) to then run MMAP (using the MM command) on it.

58. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 58 MMAP - what does the output look like? Example MMap thumbnail output from a high FOM trial cell

59. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 59 MMAP - what does the output look like? Example MMap output from a high FOM trial cell

60. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 60 MCMaile by Armel Le Bail  Developed in September 2002 (on from the ESPOIR code)  GPL’d (free and you get the source code)  Whole profile Monte Carlo and Grid Search methods using a pattern reconstituted from the peak list  Columnar peak shape - can increase/decrease width  Can make “important” trace peaks more likely to be part of a solution by increasing their intensities.  Insensitive to impurity peaks  20,000 tests per second - but can still take many hours  Thus a method of last resort

61. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 61 A MCMaile ASCII input file

62. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 62 MCMaile is running

63. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 63 MCMaile output files  Chekcell *.ckm summary file of all trial cells and Fullprof PRF profile file of top solution: viewable in Winplotr

64. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 64 MCMaile : on large cubic  Finds cubic cell easily - even with trace “impurity” peaks  Via outputted Chekcell *.ckm summary file. Top solution is not correct solution (possible effect of impurity peaks)

65. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 65 MCMaile : on large cubic  Finds cubic cell easily - even with trace “impurity” peaks  Via outputted Chekcell *.ckm summary file. Second set of solutions is correct

66. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 66 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)

67. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 67 SDPDRR-II - Indexing Results  WWW: http://sdpd.univ-lemans.fr/sdpdrr2/results/  6 returns/100 downloads = 6% return rate

68. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 68 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

69. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 69 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

70. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 70 SDPDRR-II - Sample 3  WWW: http://sdpd.univ-lemans.fr/sdpdrr2/results/  Organisers:18.881 18.881 18.881 90 90 90 (vol 6734Å 3 )  P1:13.349 13.349 9.439 90 90 90 (Tet - 1638Å 3 )  P2:18.878 18.878 18.878 90 90 90  P3:13.354 13.354 9.442 90 90 90 (Tet - 1638Å 3 )  P4:No Solution  P5:18.878 18.878 18.878 90 90 90  P6:18.88 18.88 18.88 90 90 90

71. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 71 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

72. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 72 SDPDRR-II - Sample 3: Tetragonal: 1 peak unmatched - 46 hkl’s (P42MC et al) to match 25 reflections

73. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 73 SDPDRR-II - Sample 3: Tetragonal: Running LePage shows a cubic cell (18.885Å)

74. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 74 SDPDRR-II - Sample 3: Visual inspection of cubic cell implies “bad”peak could still be an impurity

75. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 75 SDPDRR-II - Sample 3: Cubic: 37 hkl’s to match 25 reflections (I23 et al) (vs 46 hkl’s in tetragonal)

76. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 76 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!

77. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 77 Be on the lookout for bugs in the Software! Found in LePage - within Chekcell

78. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 78 The Future  The message has got through that indexing has become a bottleneck for solving structures from powder diffraction data.  New Indexing programs are being developed.  MCMaille (Free GPL’d - get the source code as well)  Bruker SVD Indexing (commercial)  Accerlys Indexing program (commercial)  EFLECH/Index (new developments due to the SDPDRR-2)

79. Lachlan M. D. Cranswick (l.m.d.cranswick@dl.ac.uk) http://www.ccp14.ac.uk Slide 79 Conclusion  Don’t give up if your lab’s favorite indexing program doesn’t work on a particular dataset  Suites like Crysfire offer a wide range of indexing tools  Follow on with Chekcell to help pin down the correct physical cell  If that does not work - whole profile methods such as MCMaille (still using Chekcell to evaluate trial solutions) Relevant web links: CCP14 Summary Page: http://www.ccp14.ac.uk/solution/indexing/ –Crysfire: http://www.ccp14.ac.uk/tutorial/crys/ –Chekcell: http://www.ccp14.ac.uk/tutorial/lmgp/ –McMaille: http://www.cristal.org/McMaille/