Fig. 5: Energies of different molecular geometries for neutral [18]annulene and the dianion.
From: The anti-aromatic dianion and aromatic tetraanion of [18]annulene

a,b, DLPNO-CCSD(T*)-F12 energies of possible conformers of 1a, 1b, 1c in their neutral form (a) and as dianions (b), calculated for optimized geometries obtained using M06-2X (hollow diamonds), MPWB1K (hollow circles) and BLYPxx (triangles; xx denotes the percentage of exact exchange, given on the horizontal axis). c, A qualitative Walsh diagram comparing π-orbital energies of a and b conformers (MOs calculated using BLYP45).