spin polarization

https://doi.org/10.1351/goldbook.ST07105
Static and dynamic spin @[email protected] effects are distinguished. The static @[email protected] of an electron spin occurs in the CH bonds of aromatic radicals where the σ-electron closest to an unpaired π-electron tends to have its spin parallel to that of the π-electron. Likewise, static spin @[email protected] arises in the π-system of conjugated radicals: the electron of the doubly occupied @[email protected] prefers to take a closer spatial position to the odd one, which spin is parallel to the latter. The effect reflects the energy unfavourable situation if an electron of opposite spin were to come nearby.
Source:
PAC, 1999, 71, 1919. (Glossary of terms used in theoretical organic chemistry) on page 1963 [Terms] [Paper]