October 2024 - Ifeffit - millenia.cars.aps.anl.gov

demo data for XAFS tutorial
by Yohei Uemura 30 Oct '24

30 Oct '24

Dear Matt, I'm wondering if the demo data for the Larch tutorials is still available. https://urldefense.us/v3/__https://youtu.be/5mYRqpAWK-o?si=MS7_aqBiYF_cQTtf… My colleague wants to learn how to use Larch from the tutorial, but the link to the demo data is expired. Best regards, Yohei -- ================================================ Yohei Uemura (Ph.D) Instrument scientist FXE beamline, European XFEL GmbH Address : Holzkoppel 4, 22869 Schenefeld, Germany Phone: +49-40-8998-6006 上村洋平所属 : FXE beamline, European XFEL GmbH, 住所 : Holzkoppel 4, 22869 Schenefeld, Germany 電話 : +49-40-8998-6006 ================================================

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larixite: a WebAtoms-like app for converting crystallographic information into XAS input files
by Matthew Newville 30 Oct '24

30 Oct '24

Hi Folks, As some of you have noticed, the WebAtoms application stopped working on millenia.cars.aps.anl.gov a month or so ago. We now have a start of an alternative at https://urldefense.us/v3/__https://millenia.cars.aps.anl.gov/larixite__;!!G… This uses PyMatGen to convert CIF files into Feff.inp files. This includes a simple searchable interface to data collected from the American Mineralogist Crystal Structure Database (https://urldefense.us/v3/__https://rruff.geo.arizona.edu/AMS/amcsd.php__;!!… ) of published mineral structures that has been included in xraylarch for some time. You can upload a CIF file – and most should work. We expect to be able to add inputs for FDMNES soon, and we’re looking into formats for other calculations (say, Ocean) as well. On a practical note, we thought it would be best to pull this code out of the main Larch repository and start a fresh project just for “working with crystallographic information and atomic clusters to generate inputs for XAS calculations”. This code is now under https://urldefense.us/v3/__https://github.com/xraypy/larixite__;!!G_uCfscf7… (and does not rely on the larger xraylarch package). At some point soon we plan to remove this code from xraylarch itself and use this project for that functionality. This is all sort of new, so suggestions on any part of this and bug reports are most welcome. --Matt

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MD EXAFS comparison with Experimental EXAFS
by awade9＠bu.edu 25 Oct '24

25 Oct '24

Hello, I'm trying to compare my experimental EXAFS data for a molten salt (NaF-ZrF4) sample (extracted through Athena), with EXAFS obtained through running FEFF iteratively on multiple atomic configuration files obtained through MD to get an average EXAFS out. This has been performed before by Pauvert et al. (https://doi.org/10.1021/jp203137h) for a similar salt as well as others for different materials. In our comparison, there seems to be a phase shift in MD EXAFS (to higher k) compared to experimental EXAFS and I would like to know if that's normal. I've read that there is an energy shift when we use FEFF and this might be affecting the MD EXAFS here but all the comparisons I've come across in literature overlay quite well... Thank you. Best, Anubhav

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SIXPACK Background Removal not reading averaged data file from SamView
by Muretta, Julie 21 Oct '24

21 Oct '24

Hello, I have been using SIXPACK to process my S K-edge XANES data from SSRL beamline 4-3. I am using SamView to average 5 scans (to improve S/N) for each sample. Then I save the averaged file (.avg) and open in the SIXPACK Background Removal application for normalization. All data sets seem to be working great with this method except one. This one opens fine in SamView, but Background Removal cannot open the averaged file. Here is the error message: *** read_data: error opening file *** C:\sixpack/test.inp pre_edge: no energy array? pre_edge: no energy array? I have saved the averaged file as a .txt file to look at it (.avg and .txt files attached), and I see an energy array. How can I open and use this in SIXPACK Background Removal? Thank you in advance, Julie Muretta

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Query regarding smoothing data
by Muskan Verma 19 Oct '24

19 Oct '24

Good morning professor Would you help me in this question. I am doing XANES analysis of N-K edge of some irradiated sample. There is a lot of noise in the data. I want to smooth the data. Which method should I prefer and how many number of data points should be taken to get a good peak to get a good fit? Kind regards

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Problem with fit data export
by Otal Eugenio 17 Oct '24

17 Oct '24

Dear all, I was exporting the filtered data and found Larch is not exporting the filtered data. No new files were found in the folder I was saving the files. I found a victory in doing it from the plotting window after fitting, File > Export data. I exported the chi(k) with chi(q), chi(k) with the fit and chi(q) with the fit. All included bellow. The signal in chi(k) with its fit and chi(q) with its fit, both match well. The fit shown chi(k) and chi(q) has different aspects. Am I wrong or the fit should look the same in both cases? Is there any compensation for the window used? Do I need to change something in the configuration to export it properly? Best regards [image: image.png] [image: image.png] [image: image.png] (^ㅇᆽㅇ^)(=˃ᆺ˂=)(=🝦 ༝ 🝦=) Eugenio H. OTAL Assistant Professor Research Initiative for Supra Materials, Shinshu University 4-17-1 Wakasato, Nagano city. 380-8553, Japan eugenio_otal(a)shinshu-u.ac.jp ¯\_(ツ)_/¯¯\_(ツ)_/¯ Who is John Galt? ¯\_(ツ)_/¯¯\_(ツ)_/¯

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Retrieving errors (uncertainties) for sigma2 = eins(temperature, thetae) in Artemis
by albeiro.henaow＠gmail.com 11 Oct '24

11 Oct '24

I am modeling the Debye-Waller factor by using the Einstein model in Artemis, where the Einstein temperature (thetae) is a guess parameter and sigma2 is a defined parameter as eins(temperature, thetae). Although, after running the fit, the error for the estimation of thetae is given by the fit report, the error for the corresponding defined sigma2 is missing. I am working on some models to reduce the errors in the estimation of the Debye-Waller factor, so it's an important value for my research. I tried to propagate the errors by using the equation in the ref paper (E. Sevillano, H. Meuth, and J. J. Rehr. Extended x-ray absorption fine structure Debye-Waller factors. I. Monatomic crystals. Phys. Rev. B, 20:4908–4911, Dec 1979. doi:10.1103/PhysRevB.20.4908.) However, I cannot obtain the same value of sigma2 when I substitute thetae into the equation from the paper compared to the value reported in the fit. Can anyone help clarify the equation (or script) used in Artemis? Thank you! Wilson Henao

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