[Ifeffit] FEFF10 simulation of Pt alloy

[Alexey Boubnov]

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 <hzhangcat at gmail.com>:

> 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
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