How to determine if a defect state is occupied or not

[sjtuzhanglei]

Dear all,

I recently found that for CeO2, MnO, or other related ionic materials, oxygen vacancy in CeO2 and Mn vacancy in MnO will create a very localized defect state in the middle of the band gap.

However, this defect polaron state is usually above the fermi level from OUTCAR. Thus, how do I know if this defect level is actually occupied or not, as the Fermi level from OUTCAR is the highest energy of occupied electrons?

What is the physical meaning of this defect state? I.e. If a O vacancy is formed, the O 2p band electrons will be excited to Ce f band polaron state; if a Mn vacancy is formed, electrons from the surrounding Mn d-band in valence band will be excited to the polaron state? I understand that in CeO2 case, it is electron polaron; and MnO is hole polaron.

Thanks!

[Neutrino]

Dear Sjtuzhanglei ,


You can check whether a defect state is occupied or not by integrating the total density of states up to right before that state. If some the electrons equals the total number of valence electrons (POTCAR electrons) , then it is unoccupied.

This is one way but I'm sure there other ideas to do this check as well.

Mostafa