# How may I calculate atomic orbital energies using VASP?

I am trying to calculate the d orbital energy of the Cu single atom, like in this page, I have tried to use the Eigenband energies minus the vacuum energy level(about 0.007eV).


k-point     1 :       0.0000    0.0000    0.0000
band No.  band energies     occupation
1      -6.8877      1.00000
2      -6.8877      1.00000
3      -6.8872      1.00000
4      -6.8863      1.00000
5      -6.8863      1.00000
6      -5.9796      1.00000
7      -0.9533      0.00000
8      -0.8847      0.00000
9      -0.5722      0.00000
10      -0.1787      0.00000
Fermi energy:        -5.7513822398

spin component 2

k-point     1 :       0.0000    0.0000    0.0000
band No.  band energies     occupation
1      -6.6023      1.00000
2      -6.6010      1.00000
3      -6.6010      1.00000
4      -6.6010      1.00000
5      -6.6010      1.00000
6      -5.2707      0.00000
7      -0.4024      0.00000
8      -0.2912      0.00000
9       0.0570      0.00000
10       0.0751      0.00000



The result is far from the experient result. My question is : how should I calculate the d orbital energy using VASP?

• Are you sure the method you used was appropriate for a transition metal species? If you are planning on using DFT (you've used it as a tag, so I assume that's what you're using), as opposed to an ab initio method, you need to make sure you pick the right functional and basis set. Nov 4, 2023 at 7:25
• In VASP, I have to use a plane-wave basis set. I already tried to use GGA or HSE06, but the results aren't consistent with the experiment. I am wondering if the pseudopotential used in VASP isn't suited for calculating the exact orbital energy of the isolated atoms.
– Jack
Nov 4, 2023 at 7:47
• I know this technically doesn’t answer the question, but my suggestion would be to use an ab initio program like ORCA, Gaussian or NWChem. That way you’ll have access to far more accurate methods that way. Unless this is a proof-of-concept calculation…? I looked up VASP, though—could you see if MP2 works? Nov 4, 2023 at 16:51
• @isolatedmatrix. I could find data using DFT to calculate the orbital energy, but the data is far from the experimental data. e.g. for the O atom, the 2p orbital energy is -0.338381 Hartree, which is absolutely not consistent with the photoelectron spectroscopy result. Here are the reference results calculated by NIST. nist.gov/pml/…
– Jack
Nov 5, 2023 at 8:38

• The model is a single atom in a box, since there have been some bands unoccupied in the result, I don't think the band structure is incomplete, I have tried to set NBAND=30, and the result is almost the same.