[Ifeffit] Correct Crystallographic parameters for Todorokite EXAFS fitting in Artemis

[Sathish Mayanna]

Hi

I am having some problem to get the real crystallographic parameters for
Todorokite (I know there are many literature available) I used the
parameters from Post et al 1988 (*Rietveld refinement of the Todorokite
structure*) and others as well (*attached Todorokite.inp file*).

I except the corner corner Mn in Todorokite, since its a tunnel structure,
but the Feff calculations do not provide any corner corner Mn, in addition
I cannot fit exactly even Mn-O or Mn-Mn.

But If I use Ramsdellite (*attached Ramsdellite.inp file*), which is also a
tunnel structure, I could get the Corner-Corner Mn and can fit perfectly
the Mn-O, Mn-Mn, but cannot fit in K space.

It would be really great, if anyone could provide me the model Tunnel
type-Mn oxide crystallographic parameters to fit the data *(attached Mn
Spectra.prj)*

p.s: I tried my best to learn and understand the crystallographic
parameters and miller indices, but still I feel that I am very poor, it
would be nice, if someone suggest some good and basic source to learn more
about pure mineralogy (which is crucial to know the basic parameters for
fitting in Artemis).
-- 
Satty
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