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Just recently got into DFT and I've been doing a few calculations on my own on Quantum Espresso. I've come up with electronic band structures for materials that I've been looking at and I was hoping to see if I'm coming up with the right conclusion regarding them. Two of them are shown below (used EV-GGA to calculate for these, could have used others, but I'm sticking to the Engel-Vosko for now)Band structure 1

Band structure 2

These are undoped materials, and so I'm seeing that these are metallic in nature. I guess my main question is, what makes the Fermi level pass through the valence or conduction band? Is it the interaction of the orbitals of the atoms in the crystal? And would doping have an effect on the position of the Fermi level in these materials (electron doping in the first case, and hole doping in the second case)?

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The 0-energy outputted by QE does not necessarily correspond with the Fermi energy. Depending on what keywords you use in your input, you can get the actual Fermi-energy outputted - you should try looking for "Fermi energy" in you scf output. In any all other cases you should get the energy of the highest occupied level - try looking for "highest occupied level" in your scf output.

After getting this value, you can always shift your band structures so that the 0-energy corresponds to either the valence band maximum, the fermi energy, or any other value of interest.

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