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

Re: [Ifeffit] Creating a structure from EXAFS fitting
by Robert Gordon 27 Jun '24

27 Jun '24

Hi Lisa, Starting from a similar crystal structure could work. Alternatively, building a basic "crystal" structure using symmetry P1 and just putting the atoms where you want them would be feasible - tedious if you have a lot of atoms, easier if you know you have higher symmetry. e.g. Test Symmetry P1 * i.e. no symmetry a = 10 b = 10 c = 10 *Angstroms, easy to scale alpha = 90 beta = 90 gamma = 90 * so metrically cubic Central atom 0.000 0.000 0.000 * at origin, could always displace by 1/2 lattice constants to keep all in the unit cell 1st NNa 0.220 0.000 0.000 * 1st nns at 2.2 Angstroms away 1stNNb 0.000 0.220 0.000 1stNNc 0.000 0.000 0.220 1stNNd -0.220 0.000 0.000 etc... I've used this for modelling molecules, surfaces (with deposited films) as well as 3D crystals. It is a bit of brute force, but should work in any crystal visualization program... cheers, -R. On 2024-06-27 8:47 a.m., Lisa Langlois wrote: > Hello XAFS friends. I would like to know how to create a structure > model for a molecule that was measured with EXAFS, then modeled using > the typical strategies? - So, in the end you have some distances and > bond angles from the central atom > ZjQcmQRYFpfptBannerStart > This Message Is From an External Sender > This message came from outside your organization. > ZjQcmQRYFpfptBannerEnd > Hello XAFS friends. > I would like to know how to create a structure model for a molecule > that was measured with EXAFS, then modeled using the typical > strategies? - So, in the end you have some distances and bond angles > from the central atom to the first, and maybe second neighbor. > I was thinking that you start from a similar crystal structure and > then adapt that model using the numbers you got from EXAFS fitting, > using for example the Vesta program. > Best wishes, > Lisa. > > > > > Lisa Langlois, PhD > Beamline scientist > Rm 144 > Phone: +1 225-578-9341 > LSU-CAMD > 6980 Jefferson Hwy, Baton Rouge, LA 70806 > https://urldefense.us/v3/__https://www.lsu.edu/camd/__;!!G_uCfscf7eWS!adSZ4… > <https://urldefense.us/v3/__https://www.lsu.edu/camd/__;!!G_uCfscf7eWS!ZSSym…> > >

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Creating a structure from EXAFS fitting
by Lisa Langlois 27 Jun '24

27 Jun '24

Hello XAFS friends. I would like to know how to create a structure model for a molecule that was measured with EXAFS, then modeled using the typical strategies? - So, in the end you have some distances and bond angles from the central atom to the first, and maybe second neighbor. I was thinking that you start from a similar crystal structure and then adapt that model using the numbers you got from EXAFS fitting, using for example the Vesta program. Best wishes, Lisa. Lisa Langlois, PhD Beamline scientist Rm 144 Phone: +1 225-578-9341 LSU-CAMD 6980 Jefferson Hwy, Baton Rouge, LA 70806 https://urldefense.us/v3/__https://www.lsu.edu/camd/__;!!G_uCfscf7eWS!ZSSym…

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Al and Si references
by Amine EL MESSBAHI 09 Jun '24

09 Jun '24

Hi, Where can I find some Al and Si K-edge normalized data? Thank you, Amine El Messbahi email: amineelmessbahi(a)outlook.com

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alpha and σ2 values for EXAFS data fitting in Artemis came negative
by Arpita Nandy 04 Jun '24

04 Jun '24

Hello Everyone, During one of the data fittings in Artemis, alpha and σ2 came negative!!! What is/are the reason/s behind it? The corresponding file is attached... Regards, Arpita Nandy, PhD student Saha Institute of Nuclear Physics, India

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