 In a more detailed analysis which considers the environment of each orbital due to all other electrons, both the 1σ orbitals have higher energies than the 1s AO and the occupied 2σ is also higher in energy than the 2s AO (see table 1).The MO diagram for diboron (B-B, electron configuration 1σ"g"21σ"u"22σ"g"22σ"u"21π"u"2) requires the introduction of an atomic orbital overlap model for p orbitals.The three dumbbell-shaped p-orbitals have equal energy and are oriented mutually perpendicularly (or orthogonally).