I am trying to do a DFT calculation of Oxygen atoms with the VASP code. My settings follow the official tutorial on the Oxygen atom of VASP. But it turns out the energy levels of the two spin components are very different, which is obviously wrong. My question is:
Why can't DFT describe the electronic configuration and energy level of a single atom? Is this issue related to the concept of "unrestricted-spin DFT"?
Here is the result:
Fermi energy: -7.3248173814
spin component 1
k-point 1 : 0.0000 0.0000 0.0000
band No. band energies occupation
1 -25.0682 1.00000
2 -10.7441 1.00000
3 -10.7433 1.00000
4 -8.6436 1.00000
5 -0.5792 0.00000
6 1.8046 0.00000
7 1.9955 0.00000
8 2.0142 0.00000
Fermi energy: -7.3248173814
spin component 2
k-point 1 : 0.0000 0.0000 0.0000
band No. band energies occupation
1 -21.4031 1.00000
2 -7.3891 1.00000
3 -6.2821 0.00000
4 -6.2806 0.00000
5 -0.3297 0.00000
6 1.9176 0.00000
7 2.1797 0.00000
8 2.4480 0.00000