[Ifeffit] How to identify Mn Mn Corner edge paths in Artemis

[Matthew Marcus]

Corner-sharing octahedra in birnessite-based structure occur either due to interlayer Mn, i.e. Mn which is attached on
top of the layer, over a layer vacancy, or octahedra hanging off the edges of sheets.  There is a vast litereature on this,
notably from people like Manceau, Bargar and Webb.  Please refer to their papers.  You can get Manceau's papers by going to
his website.  They're all available as PDF.
	mam

On 1/7/2014 3:51 AM, fred.mosselmans at diamond.ac.uk wrote:
> Hi Sathish,
>
> There are no corner sharing paths in your feff calculation as the "perfect" birnessite model you are using only has edge sharing octahedra. I am not a phyllomanganate expert so can't help with a structure suggestion to try but using google I would think you could find a structure with corner sharing MnO6.
> Then you could take the corner sharing path from there and the edge sharing from your original structure.
>
> In Sam Webb's paper he has refined his model to give shell occupancy numbers as he has a non totally crystalline structure. This is effectively the path degeneracy from the Feff calculation but you cannot refine this number in artemis, you have to refine Nmncor  or some other variable the name is irrelevant and then define the path occupancy of the corner as 1 and the S02 for this path as amp * Nmncor .
>
> Bruce's videos are pretty good in getting started in fitting from scratch, which is really not the easiest thing to do, so keep going. I assume you have watched some of them. http://www.diamond.ac.uk/Home/Events/Past_events/XAS-workshop-2011.html?mgnlCK=1339516257183
>
>
> HTH
>
> Cheers
> Fred
>
>