Hello everyone,
I have calculated electronic band structure for BeO with wurtize phase. Find the band structure in the attachment. The fermi level was indicated by horizontal red line.
fermi level = 12.754 eV and lowest occupied level = 13.308 eV. These values are not equal as you seen in graph. Its ok ? Is it possible a little diference ?
many thanks,
Dear Merve , a band gap of 13.3 eV is large but possible.
I would compare this value with what has already been published in the literature to see if the calculation results (or calculation conditions) are close to reality.
What is the problem with Fermi energy?
What is the problem with Fermi energy?
Carlos
Carlos Ariel Samudio Pérez thanks to your reply. But band gap is not 13.3 eV. band gap= lowest occupied energy-highest occupied energy= 13.3-5.7939= 7.514 eV after band calculation. This 13.3 eV is only lowest occupied energy level.
Ok, 7.5 eV band gap!. Is the value consistent with what the literature says?
I keep asking: what is the problem with Fermi energy (close to the values cited in the literature?).
Are the calculation conditions appropriate?
Should the lowest occupied energy level ("conduction band"), = 13.3 eV, and the Fermi level have the same value?
Carlos
The Fermi energy for a semiconductor is not a well defined quantity as in principle it can sit anywhere in the band gap and the density will not change. For this reason different codes do define the Fermi energy in different ways. For example, Quantum Espresso sets it somewhere in the middle of the band gap. More chemistry oriented codes prefer to have it at the maximum of the valence band. Rarely, I have seen it placed at the bottom of the conduction band.
so the first routine question is what code is used here? Are the values of the parameters meaningful and converged?
Dear Merve, I agree with Dr Roberto
Please do a good bibliographical review of articles related to the topic and be well informed about the code used for the calculations.
We are about to collaborate but the work is yours!
Good look
Carlos
Carlos Ariel Samudio Pérez Roberto D'Agosta many thanks for your support. I agree with you. I have performed this calculation Quantum Espresso. I added the band structure for BeO with wurtize phase in the attachment for example (another calculation in the literature). The fermi level is located anywhere in the band gap. Also, my calculation results (lattice parameters, band gap, direct-indirect type ) are compatible with other theoretical results in literature. Many thanks for your answer.
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