Diagram of the HOMO and LUMO of a molecule. Each circle represents an electron in an orbital; when light of a high enough frequency is absorbed by an electron in the HOMO, it jumps to the LUMO.3D model of the highest occupied molecular orbital in CO23D model of the lowest unoccupied molecular orbital in CO2
In chemistry, HOMO and LUMO are types of molecular orbitals. The acronyms stand for highest occupied molecular orbital and lowest unoccupied molecular orbital, respectively. HOMO and LUMO are sometimes collectively called the frontier orbitals, such as in the frontier molecular orbital theory.
