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Structure Determination by Powder Diffractometry Round Robin

The SDPDRR Homepage is at

The second SDPDRR started September 9th, 2002

The SDPDRR-1 is closed
Deadline was June 30, 1998

Summary :
70 download of data (see full connection statistics
4 participants 
1 submission on sample 1 (inorganic) 
4 submissions on sample 2 (pharmaceutical) 

Preliminary conclusions were given at ECM-18

See "X-raying the Web", a paper written by David Bradley about the SDPDRR results, and published by ChemWeb.

Post-deadline submissions are welcome, but will be analyzed in a different way (you should not consult the organizer's results ;-) 

Original announce :


The aim of this Round Robin is to compare efficiency of methods for structure determination from powder diffractometry (SDPD). 

Two cases are offered to your attention, ensuring that every participant will use the same data.

We believe the structures to be solvable.

1st Sample is an inorganic phase, 2nd is a pharmaceutical. The supplied data comes from conventional X-rays (Cu K-alpha) and synchrotron radiation (medium resolution). 

This is not a Round Robin on chemical analysis, indexing or Rietveld method. Therefore, formula, cell and possible space groups are given. 

Deadline is fixed June 30, 1998.
At this date, you should have completed and returned the final form

As usual for a Round Robin such as this, confidentiality will be ensured. It is important to mention this given the incentive for creating the Round Robin was due to the relatively highly charged atmosphere of some Rietveld Mailing List discussions. Participants who submit a result will receive a unique participant number by which their submission will be referred by. Participant names are initially stripped from submitted results, and result sets stored and discussed internally by participant number. Referring to results by participant number during the internal analysis process helps ensure that when discussed or published, no inadvertant "verbal gaffs" occur associating/victimising individuals with individual datasets. It is the result sets and methodology which is important to the possible success of the Round Robin. (i.e., result sets submitted via intermediatory penguins via Antartic internet accounts will be accepted! :-) ) In the case of all submissions (including negative findings) participants have the option of submitting results "anonymously" (i.e., their names and institutions will not be noted as Round Robin participants). 

This is primarily for the benefit of students and/or people who fear a negative finding may be used to "inappropriately" haunt them at a later date. Given the above mentioned "charged opinions", this may not seem an unreasonable conclusion. Any procedural flaws (and successes) evident on completion of the Round Robin will be put on the web so others intending these types of studies can learn from our mistakes. 
Thus only the individual participants will be able to recognise their own results. This is a sincere attempt of a Round Robin of this nature, and it only has the chance of generating representative results if participants are confident of the aims of the Round Robin organisers to objectively collate and report the results. 

Potential participants are encouraged (even if relatively new, or complete novices) to give this their best shot and submit their results. It is suggested that supervisors may like to give these problems to students for submission as examples of non-contrived "real world" problems. Even if the result or conclusion is that one or both structures are not solvable using certain methods or approaches, or only a partial structure was obtained; this is useful information for the Round Robin. It is possible for an individual to submit multiple results performed by different methods. It is not possible to withdraw or replace a submission, but amended results can be submitted as distinct results. 
A summary of results will be presented at the invited talk on "Trends in Structure Determination from Powder Diffraction" at the ECM-18 meeting in Prague. 

Copyright © 1998 L.M.D Cranswick & A. Le Bail

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