[Wien] Calculation fo difference of Fermi energies between tantalum and mercury telluride

[Peter Blaha]

i) Your surface structures are all in P1 symmetry. This leads to a 
10-100 times larger computational effort than necessary.
Remove ALL labels from the atoms in your struct files ("Ta1" --> "Ta ", 
and so on), and use x nn or x sgroup to generate structures which 
exploit symmetry.

ii) You said: " I find that the work function for Ta and HgTe are similar".
In order to calculate the work function you need the zero of energy, but 
you said, you cannot determine it. I do not understand how you 
calculated the work function.

iii) Your surface slabs can be set up with vacuum in the middle of the 
cell (at z=0.5) or at the origin (z=0). Depending on that, you look in 
case.scf at
:VZERO    at v0   or   v5  (coulomb potantial, should be a positive number).
This number is your "reference energy" and the work function follows as 
difference between EF and vzero. This also gives you EF on an absolute 
scale.
PS: Make sure, your vacuum is thick enough, maybe do 2 calculations with 
different vacuum and compare the results.



Am 09.06.2024 um 14:49 schrieb Amlan Ray via Wien:
> Dear Prof. Blaha,
> 
> I formed Slab structures for Ta and HgTe (attached .struct files) and 
> ran WIEN2k 21 version. From the output (.scf files), I find that the 
> work function for Ta and HgTe are similar. However, I am interested to 
> know their difference of Fermi energies. I cannot determine the zero 
> energy of the calculation in the two cases. I shall think that the Fermi 
> energy of Ta (a metal) would be significantly higher than that of HgTe ( 
> an insulator).
> Could you kindly help me in determining the difference of Fermi energies 
> of Ta and HgTe?
> 
> With best regards
> 
> Amlan Ray
> Variable Energy Cyclotron Center
> Kolkata, India
> 
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-165300
Email: peter.blaha at tuwien.ac.at    WIEN2k: http://www.wien2k.at
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