Flat bands around E = 0 eV|
- Date: 2020/09/27 05:23
- Name: Malone
I have another question, this time regarding band structure calculations.
When I take a slab consisting of 20 atoms, for example, and conduct a calculation, in the end
I get flat lines on a band diagram around 0 eV, where the program puts the chemical potential.
At the other hand, if I count occupied bands by hand, the result is more acceptable.
For example, I have 150 valence electrons in a spin-polarized calc, I have 150 occupied bands,
so the LUMO will be 151st from the bottom. I extract energies for this 151st bands directly
from the .Band file and it occurs to be around +60 eV, but bands do look like... bands, not just flat
lines. I had encountered similar behaviour in quantum espresso, so this is not a complete surprise.
Nevertheless, when I take a flat graphene sheet, I get the Dirac point exactly at 0 eV at K point.
This is what confuses; maybe I do not understand completely what do the codes do when they place the E=0 mark.
Could you describe what is going on here, please?