Open Data in Crystallography - Petition

Hello, For those asking for atomic coordinates at this mailing list. If you have difficulties in accessing the crystallography databases (CSD, ICSD, CRYSTMET, ICDD), you may consider to give your opinion by signing the petition in favour of opening the access to crystal data on the Web. Visit

correlation matrix

Dear all, I suspect that in my rietveld refinements i have severe correlation problems. Is there any way of having a look at the matrix where this correlations arestood out? Thanks Gerard

RE: correlation matrix

Title: Message Gerard, In GSAS there is a GENLES "print" option that will give the covariance terms larger than +/- 0.5 in the list file. There aren't as many large ones as you might think apart from the various background terms. Bob Von Dreele R.B. Von Dreele IPNS Division Argonne

introduction + question

Alexander: I just finished combined X+N refinement of similar battery materials but w/o V with Li in 2a site and Mn, Co and Ni in 2b (or vise versa). Chemical composition was well known; The problem we were looking for was migration/exchange of transition metal from 2b to 2a. That's not so simple

introduction + question

Since we're on the subject of battery materials, we published some work recently where we didn't assume that it was the Ni that went to the Li site in LiMn1/3Ni1/3Co1/3O2. It's logical if it's Ni2+ but we had the data to test it in the form of resonant scattering data to add some more

introduction + question

We didn't assume that Ni goes to the Li sites it was the only choice confirmed by others, and it is not so simple as the full occupancy and stoichiometry should be measured accurately. BTW sample composition as well as sample preparation is a very crucial factor where and what goes. I believe that

introduction + question

That's right. The assumption was made just to simplify discussion; in reality of course there were no assumptions. By the way in that particular case it is possible to refine more that 1 occupancy (Ni/Li), e.g. total metal content. Peter Peter Y. Zavalij Director, X-ray Crystallographic

introduction + question

Peter It sounds like you were able to refine on the occupancies without physically unreasonable site occupancies. I am also sure that you have simplified the discussion for clarity. This is fine but I would add as a hint to Alexander that making a number of series of samples can assist greatly in