<div dir="ltr"><br><br>Dear Prof. Blaha,<br><br>Thank you very much for your reply!<br><br>This is very helpful.<br><br>Let me focus on my current approach, without considering PE or BSE, so<br>I can better explain what I am doing.<br><br>1. I create an excited state distribution (single particle picture)<br>by removing some electrons from valence bands to conduction bands,<br>just like TDDFT calculation. This is fed into lapw2.F to overwrite weigh.<br><br>For instance, around "FERMI level", my weight file looks like this.<br> Energy K-weight x occupuation<br> -7.006876394079 0.13707228701714D-02<br> -7.005370729925 0.13708743753079D-02<br> -7.005042197147 0.13709258712878D-02<br> -6.955685793309 0.13706667569952D-02<br> -6.954117252455 0.13704002422584D-02<br> -6.954115357204 0.13698089586212D-02<br> -5.936189328670 0.13710737741162D-02<br> -5.707575434173 0.13678085576708D-02<br> -4.187063164686 0.13624145475869D-02<br> -4.185285376071 0.13627677058236D-02<br>...<br> 0.561216622892 0.13159990040964D-02<br> 0.571698115465 0.12841250626557D-02<br> 0.572675622534 0.12920402275963D-02<br> 0.581408911740 0.12929368390139D-02<br> 0.587122479196 0.12638067890570D-02 <---Nominal "Fermi level"<br> 0.624650919328 0.11575060746309D-03 <br> 0.629635584357 0.58852070187352D-04<br> 0.635765764218 0.76069983586581D-04<br> 0.664550772055 0.79231428253519D-04<br> 0.667904320058 0.41660338621999D-04<br> 0.702333139421 0.95709602531662D-04<br>...<br> 2.200294635520 0.25778331730391D-04<br> 2.214731483047 0.47148654345984D-04<br> 2.277512135430 0.18778395329644D-03<br> 2.281816619070 0.18308654544186D-03<br><br>2. I carry out a self-consistent calculation with the above fixed<br>weight but with a lower charge convergence criterion -cc, with two choices.<br><br>(a) If I directly run with case.inm (first line),<br>MSR1 0.000 YES <br><br>Wien gives FERMI ERROR, since it finds few electrons than RNTOT.<br><br>(b) However, if I put the difference between NOS(1) and RNTOT <br>into case.inm like,<br><br>MSR1 0.600 YES <br><br>WIEN runs without FERMI ERROR.<br><br>So my questions are, (1) How does LAPW2 include the background charge<br>from case.inm which is supposed to be used in the mixing? (2) is<br>my approach (b) meaningful?<br><br><br>Thank you so much for your help in advance!<br><br>Best wishes,<br><br>Guoping<br><br><br></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, Sep 17, 2020 at 6:52 AM Peter Blaha <<a href="mailto:pblaha@theochem.tuwien.ac.at">pblaha@theochem.tuwien.ac.at</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Hi,<br>
<br>
It is not quite clear to me what you acutally want to do.<br>
<br>
When you do photoemission, why do you want to occupy conduction band <br>
states ?<br>
<br>
Core hole calculations are for core-photoemission the proper choice.<br>
For valence photoemission we usually neglect the hole in the valence <br>
bands - although this can be a crude approximation for more localized <br>
states.<br>
<br>
In optical spectroscopy one would do what you describe: transfer a <br>
valence electron into the conduction band.<br>
The best approach would be to use the Bethe-Salpeter approach (the BSE <br>
code is available on request for WIEN2k - see unsupported software). <br>
This treats excitonic effects quite accurately, but is also quite <br>
demanding (needs a large computer cluster).<br>
<br>
If I understand your approach correctly, you reduced the number of <br>
valence electrons and put the missing charge as background ??<br>
In this way you excite only electrons at the VBM !!!<br>
How many electrons would you remove ? If you remove 1 electron, you <br>
remove it in every unit cell of your infinite crystal !! This is not <br>
what happens in experiment.<br>
You could create a supercell (eg. 2x2x2) and excite 1 e, but again, <br>
usually this is "delocalized" and you will remove 1/8 of an electron in <br>
each cell of the whole crystal.<br>
<br>
PS: "Technically" it should still be possible to use a "2-window" <br>
calculation (previously used for semicore states) in WIEN2k. You can run <br>
lapw2 two (3) times, once with NE-1 electrons and once with NE+1 <br>
electrons and set an appropriate EMIN in lapw2 (x lapw2 -sc -emin xxx), <br>
where xxx could be EF of the ground state). Mixer will then add the <br>
clmval and clmsc files together. But you always have the problem: you do <br>
this for the whole crystal).<br>
<br>
Am 15.09.2020 um 22:26 schrieb Guoping Zhang:<br>
> Dear Professor Blaha and Wien users,<br>
> <br>
> I am interested in states in conduction bands, but I am not interested <br>
> to get a Fermi energy (and I have no Fermi error in the ground state run).<br>
> I occupy some conduction states (removing some from valence bands) with <br>
> some electrons by changing the weight files. If I use the Tetrahedral <br>
> method, this leads to Fermi error in fermi.F at SOS. (TEMPS option in <br>
> case.in2 is not ideal for my case). So I calculate the electron <br>
> difference between NOS(1) and RNTOT in the NOS subroutine, and put this <br>
> difference into case.inm as a background charge. Wien2k runs without <br>
> an Fermi error message, but I wonder<br>
> (1) whether this is a sound approach.<br>
> (2) whether there is any other better method, besides creating a core <br>
> hole in case.inc file.<br>
> (3) whether this method can be used to treat photoemission, where <br>
> electrons are knocked out of the system.<br>
> <br>
> Any comments and suggestions are welcome. If you need more information, <br>
> I will be happy to provide.<br>
> <br>
> Thank you very much for your help and attention!<br>
> Best wishes,<br>
> Guoping<br>
> <br>
> <br>
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna<br>
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