Beryllium Be²⁺ (valence electrons)

Oxygen O²⁻ (valence electrons)

Wave functions 2Be²⁺ & 2O²⁻

Band gap (Γ-Γ) in eV

1

1s²2s⁰2p⁰

2s²2p⁶

36

10.630

2

1s²2s⁰2p⁰3p⁰

2s²2p⁶

48

10.296

3

1s²2s⁰2p⁰3p⁰4p⁰

2s²2p⁶

60

10.300

4

1s²2s⁰2p⁰3p⁰4p⁰4s⁰

2s²2p⁶

64

9.182

5

1s²2s⁰2p⁰3p⁰4p⁰

2s²2p⁶3s⁰

64

7.58

6

1s²2s⁰2p⁰3p⁰4p⁰

2s²2p⁶3p⁰

72

9.388 (Indirect)