Pearson R G
Chemistry Department, Northwestern University, Evanston, Illinois 60201.
Proc Natl Acad Sci U S A. 1975 Jun;72(6):2104-6. doi: 10.1073/pnas.72.6.2104.
Jahn-Teller effects are grouped into two categories. The first arises from incomplete shells of degenerate orbitals. It includes the first-order Jahn-Teller effect, and the pseudo Jahn-Teller effect. The second arises from filled and empty molecular orbitals that are close in energy, and is the second-order Jahn-Teller effect. The two categories have quite different physical bases. As a result, geometric distortions produced by the first are quite small and normally lead to dynamic effects only. In favorable cases, the second-order Jahn-Teller effect produces very large distortions, including complete dissociation of a molecule. This can occur even when the relevant molecular orbitals are separated in energy by as much as 4 eV.
Jahn-Teller效应分为两类。第一类源于简并轨道的未填满壳层。它包括一级Jahn-Teller效应和赝Jahn-Teller效应。第二类源于能量相近的满分子轨道和空分子轨道，即二级Jahn-Teller效应。这两类效应有着截然不同的物理基础。因此，第一类效应产生的几何畸变非常小，通常仅导致动态效应。在有利的情况下，二级Jahn-Teller效应会产生非常大的畸变，包括分子的完全解离。即使相关分子轨道在能量上相差多达4电子伏特，这种情况也可能发生。
