HOMO and
LUMO are
acronyms for
highest occupied molecular orbital and
lowest unoccupied molecular orbital, respectively. The energy difference between the HOMO and LUMO is termed the
HOMO–LUMO gap. HOMO and LUMO are sometimes referred to as
frontier orbitals. The difference in energy between these two
frontier orbitals can be used to predict the strength and stability of
transition metal complexes, as well as the colors they produce in solution.