', also called 'HOMO
') and the S
). Subjacent orbitals are sometimes found to play an important role in the interpretation of molecular interactions according to the frontier orbital approach.
PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1169 (https://doi.org/10.1351/pac199466051077)