January 2021 - Ifeffit - millenia.cars.aps.anl.gov

Nanocrystalline NiO
by Christian Wittee Lopes 18 Jan '21

18 Jan '21

Dear all, Firstly I would like to wish you a much better year than in 2020. Does anyone have some spectra of nanocrystalline NiO (not bulk standards)? I have a spectrum of a mixed compound and would like to get more insights into what I really have in this sample. Thank you in advance!!! Kind regards, -- *Christian Wittee Lopes* *Visiting Researcher* ANP/FINEP - PRH50 Institute of Chemistry, Universidade Federal do Rio Grande do Sul (UFRGS) Phone: +55 54 992430264

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Larch: AttributeError
by Rachita Rana 13 Jan '21

13 Jan '21

Hi Everyone, I am using Larch for reading and fitting EXAFS data and I get the autobk and Fourier transforms working. But when I try to generate the fefffpaths and fit the data I get an error from the feffit function. I am using the developer version of Larch on MC OS Catalina. Below is the error and the sample script- runfile('/Users/rachita/Box/Larch/Feff_Try2/001.py', wdir='/Users/rachita/Box/Larch/Feff_Try2') Traceback (most recent call last): File "/Users/rachita/Box/Larch/Feff_Try2/001.py", line 27, in <module> fit = feffit(params, dset) File "/Users/rachita/opt/anaconda3/lib/python3.8/site-packages/xraylarch-0.9.50-py3.8.egg/larch/xafs/feffit.py", line 534, in feffit ds.prepare_fit(params=params) File "/Users/rachita/opt/anaconda3/lib/python3.8/site-packages/xraylarch-0.9.50-py3.8.egg/larch/xafs/feffit.py", line 265, in prepare_fit ikmax = int(1.01 + max(self.data.k)/trans.kstep) AttributeError: 'AthenaGroup' object has no attribute ‘k’ #tried this with xdi format data and got the same error Below is the script - #!/usr/bin/env python3 # -*- coding: utf-8 -*- from larch.fitting import param_group, Parameter from larch.io <http://larch.io/> import read_xdi from larch.xafs import feffpath, feffit_dataset, feffit_transform, feffit, feffit_report data = read_xdi('cu_metal_rt.xdi’) #I tried importing Athena project file too path1 = feffpath('feff0001.dat', s02='amplitude', e0='del_e0', sigma2='sigma2', deltar='del_r') trans = feffit_transform(kmin=3, kmax=16, kw=(2,1,3), dk=1, window='hanning', rmin=1.7, rmax=3.1) params = param_group(amplitude= Parameter(1, vary=True), del_e0 = Parameter(1e-7, vary=True), del_r = Parameter(1e-7, vary=True), sigma2 = Parameter(0.003, vary=True)) dset = feffit_dataset(data=data, pathlist=[path1], transform=trans) fit = feffit(params, dset) print(feffit_report(fit)) By printing path groups and transform fit, I confirmed that the data is read correctly. Please let me know if there are ways to fix this or if there is an error in my script. Thank You! Rachita

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Artemis\Plot mismatch\Artemis[Plot]&Artemis [Feff] Atoms and Feff
by Huaming 11 Jan '21

11 Jan '21

Dear all, I am using Artemis for EXAFS data fitting and found that the |χ(R)| plot shown in "Artemis [Plot]" and "Artemis [Feff] Atoms and Feff" are in great difference for a same scattering path. However, the |χ(k)| plots shown in the above two windows is the same. For the plot shown in "Artemis [Feff] Atoms and Feff" window, one path is selected and 'Plot path' is clicked. For the plot shown in "Artemis [Plot]", the same path is dragged into the "Artemis window" and then transfered path and plot in R by click "Action" menu. I would like to know what is the difference of data shown in the two windows. BTW, whether it is possible to have two peaks in the |chi(R)| plot for a single scattering path? For some scatters with high-Z, the f(k) may feature multiple peaks. Thanks, All bests, Huaming Hou

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