[Ifeffit] High SO2

[Kaustubh Priolkar]

If I could add to the discussion and understand a bit more from it, Does Scott mean that when the structure is kind of unknown or is disordered then one follows the approach practiced by Abhijeet. Whereas when one has a crystalline system - there is no merit in fixing the parameters of the first shell and adding more paths to it. If this is the case then I would like to agree with Scott based on my experience in analyzing data on Ni2MnGa type alloys in austenitic phase and martensitic phase. 

Kaustubh

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Dr. Kaustubh R. S. Priolkar 
Department of Physics, 
Goa University 
Taleigao Plateau, 
Goa 403 206 India
Phone (O): 91-832-6519340
(R): 91-832-2412235
Fax: 91-832-2451184
email: krp at unigoa.ac.in
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----- Original Message ----
From: Matt Newville <newville at cars.uchicago.edu>
To: XAFS Analysis using Ifeffit <ifeffit at millenia.cars.aps.anl.gov>
Sent: Saturday, 11 April, 2009 2:25:00 AM
Subject: Re: [Ifeffit] High SO2

Scott,

I read Abhijeets's
    But what I know about fitting is that we have to first fit the
first shell and then
    keeping the first shell  parameter constant , we go for the next shell

and Jeremy's
  I typically perform the fitting as you suggest, at least in
complicated systems, one shell at a time.

to mean they fit one shell at a time, that is: when the second shell
is being fitted, the first is not and the fit R-range is changed for
the 2nd shell fit to not include (most of) the first shell.   As you
say,  there is very little value in having the R-range include the
first shell if you're not actually adjusting parameters that affect
that part of the spectrum.

--Matt
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