In this video of benzene orbitals, a lot of different orbitals are presented. Even orbitals that, I assume, could never be occupied. What is the purpose of calculating all these orbitals? Isn't all the chemical information needed (bonding, reactions) coming from the HOMO and LUMO (FMO theory)?
Here is an image of a few of the orbitals shown in the video:
Energy diagram of the molecular orbitals explored for the D6h structure (left) and the D3h distorted geometry (right)
(from David Casanova and Pere Alemany, Phys. Chem. Chem. Phys. 2010, 12, 15523-15529. DOI:10.1039/C0CP01326A)