Fermi energy and Fermi momentum from first principles

[sidiq]

Hi everyone!

I run the software ABINIT. It allows one to model solids as a plane-wave pseudopotential. Since it is based on first principles DFT, we are able to obtain the energies over many k-points. This would give us a band structure.

Besides this, the calculation would print out a Fermi energy and Fermi energy is related to Fermi momentum as given in scienceworld.wolfram. com/physics/FermiMomentum.html

My first question is How does ABINIT obtain the Fermi energy? Secondly, can I directly convert ABINIT's Fermi energy with the Fermi momentum as given in the above link?

I am the first to admit that I should post this question in abinit forums. Unfortunately, support is a little slow there. I am simply banking on someone who has worked with these kinds of codes before and might have some idea how the Fermi energy was calculated in terms of k-points and energies. Thanks so much for your time.

 

[rigetFrog]

Without having used any fancy software, you can numerically crunch the fermi energy from the band structure. A simple version of this is shown in the first few chapters of ashcroft and mermin solid state for a free electron gas.

I would start off by converting the k resolved electronic structure into the density of states, and then populate the available states with your valence electrons, starting with the lowest energy first, until you run out of available electrons.