[Ifeffit] Plotting chi(R) from FEFF in XAS Viewer (Larch) with

[Mosselmans, Fred (DLSLtd,RAL,SCI)]

Dear Matt and Carlo and Liam,

I agree with Matt and Carlo that phase corrected plots are not a great idea, I think they lead people to forget that they are not looking at a radial distribution function  and encourages people to think they can read distances off  a plot of the amplitude of the FT of overlapping sine waves reliably.

Thanks
Fred


J F W Mosselmans
Principal Beamline Scientist I20
Diamond Light Source
Harwell Campus
Didcot
OX11 0DE

01235 778568
Fred.mosselmans at diamond.ac.uk
07419362123


Message: 1
Date: Tue, 13 Dec 2022 16:53:03 -0600
From: Matt Newville <newville at cars.uchicago.edu>
To: XAFS Analysis using Ifeffit <ifeffit at millenia.cars.aps.anl.gov>
Subject: Re: [Ifeffit] Plotting chi(R) from FEFF in XAS Viewer (Larch)
	with phase correction
Message-ID:
	<CA+7ESbr+dCT8hfwNtm2T+ToNyHQW4iqwfBbBJoECN4ESE+iscg at mail.gmail.com>
Content-Type: text/plain; charset="utf-8"

Hi Liam,

Yes,  this is not currently available.  It would not be hard to enable, but I am not sure it is a great thing to do. I admit that I sort of find that phase-correction plots need a lot of explanation, and so are prone to causing confusion.  They might be useful for Pt metal, but they cannot really be correct for multi-atomic systems.  Well, I guess "correct" is not the only consideration ;).

I guess I would ask if there are suggestions and input from people teaching XAFS on whether phase corrections (and probably a handful of other "tricks"
or analysis variations) are actually useful or just confusing.




On Tue, Dec 13, 2022 at 7:58 AM Liam Nagle-Cocco <lavn2 at cam.ac.uk> wrote:

> Dear all,
>
> In Artemis it is possible to plot chi(R) for FEFF-fit, with the phase 
> corrected - i.e. bond length corrected for deltaR. This is shown in 
> this screenshot below ("Use this path for phase corrected plotting"). 
> Is this possible in XAS Viewer?
>
>
> Liam Nagle-Cocco *(he/his)*
>
> PhD Student in Condensed Matter Physics | Cavendish Laboratory
>
> Welfare Officer 2022-2023 | Jesus College MCR 
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--
--Matt Newville <newville at cars.uchicago.edu> 630-327-7411
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