I believe it is using (or intends to use) 

    lifetime = hbar /gamma

which is what Krause et al give.  With gamma = 0.2 eV, and hbar ~= 4.13567e-15 eVs, then lifetime is ~20fs.  

Maybe I'm missing something more subtle?  FWIW, these reported numbers for gamma in eV are described by Krause et al as "FWHM".

--Matt

On Mon, Sep 28, 2020 at 1:13 PM Daniel Przyrembel <daniel.przyrembel@fu-berlin.de> wrote:

Hi Matt,

Thanks for the quick reply!
However, I seem to not have made clear my concern...

The widths in energy (eV) are fine.

However, in "Hephaestus", the "souped-up periodic table for the X-ray
absorption spectroscopist", these level widths in energy (eV) are also
given as equivalent lifetimes (in fs), however incorrectly: A level width
of ~0.2 eV in fact corresponds to a lifetime of ca. 3 fs, not ~30 fs as
given there.

Those lifetimes shown in Hephaestus all seem to be off by a general factor
of 10. I guess that is just the energy width/lifetime conversion gone
slightly wrong...
I imagine I'm not the only one using Hephaestus as a convenient tool to
look stuff up quickly, so I thought it might be useful to point out this
flaw.

Just to make sure, I have again imported the xraydb: That has not changed
Hephaestus' behavior in terms of the lifetime info (I'm using the latest
64-bit version on Windows).


> Hi Daniel,
>
> Thanks - that does seem wrong.  FWIW, Larch uses XrayDB which uses
> corehole
> widths from Krause and Oliver for Z>10 and Keski-Rahkoken nand Krause for
> Z<10.
> For the F K edge, this give 0.2089 eV.  For this or other core-hole
> widths,
> and assuming you have Python installed, try:
>
>   ~> pip install xraydb
>   ~> python
>   >>> import xraydb
>   >>> xraydb.core_width('F', 'K')
>   0.2089
>
> Or install Larch and use
>
>    ~> larch
>    larch> core_width('F', 'K')
>    0.2089
>
>
>
> On Mon, Sep 28, 2020 at 12:08 PM Daniel Przyrembel <
> daniel.przyrembel@fu-berlin.de> wrote:
>
>> To Whom it may concern,
>>
>> I am quite sure there is a general lifetime/energy-width conversion
>> error
>> in Hephaestus: All core-hole lifetimes seem to come out too long by a
>> factor of - as it seems exactly - 10:
>> E.g. the lifetime of the F K-edge with a width of 0.25 eV is given as
>> 25.30 fs instead of ca. 2.6 fs (width = h_bar / lifetime).
>>
>> This glitch was present in 0.9.25 already and, as I noticed after
>> updating, prevails in 0.9.26. I have not tried earlier versions.
>>
>> Best regards,
>>
>> Daniel
>>
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--

--Matt Newville <newville at cars.uchicago.edu> 630-252-0431