Why Fermi level is not highest occupied state KS energy

[z9wang]

Dear VASP developers,

I am running calculations on Eu2+ doped systems. I notice that the Fermi level for some cases is far away from (below) the KS energy of the highest occupied state. Here is an abnormal example dataset.

--------------data from OUTCAR----------
band No. band energies occupation
582 1.8390 1.00000
583 1.8743 1.00000
584 1.8805 1.00000
585 4.8448 1.00000
586 4.8479 1.00000
587 4.8687 1.00000
588 4.8796 1.00000
589 4.8905 1.00000
590 4.9007 1.00000
591 4.9295 1.00000
592 6.3960 0.00000
593 7.2564 0.00000

E-fermi : 2.1173 XC(G=0): -9.7156 alpha+bet :-11.0501
-----------------------------------------------------------
We can observe that E-ferim(2.1173 eV) is much smaller than the highest occupied state energy (4.9295eV). The Fermi level may be not the exactly the energy of the highest occupied state, but my understanding is that it should be at least close to this energy. So I am wondering why this happens?

Thanks a lot.

Best
Zhenbin

[support_vasp]

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