a) Missing DOS of core states:
You calculate the DOS on an E-grid with a spacing of 3 mRy. Your core
states have such a small band dispersion (eg. just one 1mRy, but
sometimes even below; check the band ranges), and their energies fall
BETWEEN your DOS E-grid, so on your grid there is really no DOS. In
case.outputt you should see that at the expected energies, the
"integreated DOS" increases from one energy mesh to the next by 2, 6 or
even 14 electrons, although the DOS at these energies is always zero.
In essence: It is meaningless to "plot a DOS" of these localized states,
as it would corresponds to almost a delta-peak at a particular energy.
Also note, that in DFT the energy of a core level has really no
particular meaning anyway and will be far from any measurement (10 %
error in E-position)
b) XPS of 4f core states:
I would strongly recommend to put these states into the core. This can
be done conveniently during init_lapw in lstart, by not using an Energy
criterium (like -6 or -8 Ry), but a "localization criterium" like 0.999
. If you check the localization of the 4f states during lstart, you will
see that nearly everything is within the atomic sphere.
The advantage of this core treatment is 2-fold: spin-orbit coupling is
included nearly exactly (and not approximative in lapwso); and a
"half-core hole" calculation based on Slaters transition state theory
should even give you fairly accurate absolute energies.
Remember: the core states are recalculated in the modified crystal
potential, so the effect of charge transfer, ... is covered. A direct
hybridization with other states is anyway zero (as you can see from your
band width when you put them as semicore state) and there is no need to
allow for it in principle (but spoiling the much more important
spin-orbit coupling). It is in general NOT true that inclusion of more
core states increases the "accuracy" ....
Am 01.02.2017 um 13:07 schrieb Yevgen Melikhov:
Dear WIEN2k users,
I recently started studying ReSi2 and was immediately puzzled while
doing basic SCF and DOS calculations.
The structure file is attached, RMT of Re is 2.2, RMT of Si is 2.03.
Initialization was done with the following parameters:
init_lapw -b -vxc 5 -ecut -8 -rkmax 8 -numk 1000 -sp
Checking the output (also attached) I can see that:
For Re
States 1s, 2s, 2p, 3s, 3p, 3d, 4s, 4p, 4d are treated as core states
States 5s, 5p, 4f may be considered as semi-core states (energy range:
-6.29…-3 Ry)
States 5d, 6s are considered as valence states
For Si:
States 1s, 2s are treated as core states
States 2p may be considered as semi-core states (energy around: -7 Ry)
States 3s, 3p are considered as valence states
After Running SCF calculations with:
runsp_lapw -p -ec 0.00001 -cc 0.0001 -NI
and calculating DOS, I found out that I do not see 4f of Re (which I
expect to be at -40 eV as a huge peak), 5s of Re (-80 eV), or 2p of Si
(-90 eV) at all (!!!) Please see attached the figures of DOS. (I also
attach int-file to make sure that I did want DOS starting from -10.5 Ry)
I am really puzzled with this and will be grateful for any
comments/suggestions.
P.S. My ultimate goal is to calculate XPS spectra to be able to see
4f7/2 and 4f5/2 splitting. I guess for this I will have to introduce a
hole (?) in a semi-core state. I know how to do that in a core-state but
I am not sure how to do that for a semi-core. Any comments/suggestions
on this matter will be received with much appreciation as well.
Thank you in advance for your help,
Yevgen Melikhov.
(Institute of Physics PAS, Warsaw)
_______________________________________________
Wien mailing list
Wien@zeus.theochem.tuwien.ac.at
http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
SEARCH the MAILING-LIST at:
http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
--
--------------------------------------------------------------------------
Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-165300 FAX: +43-1-58801-165982
Email: bl...@theochem.tuwien.ac.at WIEN2k: http://www.wien2k.at
WWW: http://www.imc.tuwien.ac.at/staff/tc_group_e.php
--------------------------------------------------------------------------
_______________________________________________
Wien mailing list
Wien@zeus.theochem.tuwien.ac.at
http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
SEARCH the MAILING-LIST at:
http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
