Okay, there might be the issue: h ~= 4.136e-15 eV s h_bar ~= 6.582e-16 eV s So if actually h is used instead of h_bar, then that gives the lifetimes 2*pi ~= 10 times too long! I did not consider it could be due to that... But it apparently is.
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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