[Ifeffit] Core-hole Lifetimes in Hephaestus 0.9.26

[Matt Newville]

Hi Daniel,



On Mon, Sep 28, 2020 at 2:15 PM Daniel Przyrembel <
daniel.przyrembel at fu-berlin.de> wrote:

> Hi Matt,
>
> Well, independent of what Krause et al. have done, the correct uncertainty
> relation between core-hole widths as FWHM (full width at half maximum) and
> the lifetime is
>
> lifetime = h_bar / FWHM
>
> from the corresponding half-width (HWHM) expression
>
> HWHM x lifetime >= h_bar / 2
>
> Again, I just stumbled upon this when using Hephaestus, and the lifetimes
> were all oddly "long".
> The above relations are often garbled up due a HWHM-FWHM mix-up (the HWHM
> being the "spread" of the Cauchy/Lorentz/Breit-Wigner distribution towards
> higher and lower energy around the center etc.) as well, giving factor of
> two errors...
>
>
Yeah, I think most of us in the X-ray spectroscopy community think in eV
and not in fs.  ;) But it would obviously be better to report those
lifetimes better too.

I don't really have a strong feeling on whether reporting FWHM or HWHM (or
sigma, for non-Lorentzians), but consistency is good.  For sure, the values
from Krause et al are well-used in the X-ray spectroscopy community.  But,
well should that 'lifetime' be a 1/e value?

--Matt
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://millenia.cars.aps.anl.gov/pipermail/ifeffit/attachments/20200928/6731ed93/attachment.htm>