Re: [Ifeffit] FEFF10 simulation of Pt alloy

Dear all, I appreciate your kind help! I followed your instructions and now the simulation improves a lot! I will also follow the suggested papers mentioned in the emails. Have a nice day! Best, Harry On Mon, Jan 16, 2023 at 4:11 PM Alexey Boubnov wrote:

Dear Harry,

To a good approximation, using a decreased lifetime broadening works for simulating HERFD-XANES. See https://doi.org/10.1021/jp063416t where conventional and HERFD XANES are calculated with FEFF by decreasing the broadening (Fig. 2). This is done in the EXCHANGE card, e.g. to decrease the HWHM by 1.5 eV, apply on the 3rd number: EXCHANGE 0 0.0 -1.5 -1

To use the default tabulated Pt L3 broadening (about 5 eV), use 0 (EXCHANGE 0 0.0 0 -1 )

Note: experimentally this is not entirely accurate, because in HERFD you select the Pt L-alpha1 line, while in TFY you integrate over ~300 eV of this line, taking all other transitions as well. For a detailed explanation see https://doi.org/10.1016/j.cattod.2008.11.019 (Fig 2). But it should represent the results pretty well.

Also note that specifically for Pt L3, the best match of the simulated white line with experiment is obtained by ignoring the core-hole (assuming its full screening), by applying the COREHOLE NONE card option. If this is not done (COREHOLE FSR or RPA is used), the white line intensity is strongly under-estimated, at least in Pt metal. See https://doi.org/10.1023/A:1013849814153 for example and explanation.

Best regards, Alexey

Am Mo., 16. Jan. 2023 um 12:45 Uhr schrieb Andy Zhang

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Dear all,

I tried to use FEFF10 to simulate the XANES of Pt alloy (Pt L3 edge), and the simulation results fit the XANES collected using TFY mode. However, the white line intensity of the simulated XANES is much lower than the experiential spectra collected using HERFD mode.

I wonder if there is way to fit the HERFD XANES results through simulation (in other words, to increase the white line intensity of the simulated XANES).

Thanks a lot in advance!

Best, Harry _______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit

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