To complement the magnetic criteria, we examined geometry-based aromatic/antiaromatic indices, including the harmonic oscillator model of aromaticity (HOMA) and its improved version, HOMAc, considering both aromatic and antiaromatic compounds. These indices provide insights into the bond length alternation patterns that are characteristic of aromatic and antiaromatic systems. For our calculations, we consistently defined the ring as encompassing all 24 carbon atoms of the isophlorin skeleton, as this was the most relevant conjugation pathway by comparison with other pathways (for 1e, Figure ) and localized orbital locator of π orbitals(LOL-π) analysis (Figure ), which visualized π-electron localization and delocalization within the molecule.