Even-electron atomic or molecular systems whose electron configurations consist of doubly occupied orbitals.
Source: PAC, 1999, 71, 1919. (Glossary of terms used in theoretical organic chemistry) on page 1930 [Terms] [Paper]
Citation: 'closed shell molecular systems' in IUPAC Compendium of Chemical Terminology, 3rd ed. International Union of Pure and Applied Chemistry; 2006. Online version 3.0.1, 2019. https://doi.org/10.1351/goldbook.CT07010 RISBibTexEndNote