## Renner–Teller effect

https://doi.org/10.1351/goldbook.R05290
Molecular distortion in linear molecular species with degenerate electronic states (e.g. belonging to the $$C_{\infty\text{v}}$$ group). The Renner–Teller effect is a particular case of the @J03361@. From the point of view of the potential energy surfaces the Renner–Teller effect generates a surface touching (see scheme below).
Notes:
1. The Renner–Teller effect arises from splittings in the vibrational levels of molecular entities due to even terms in the vibronic perturbation expansion. This is generally a minor effect for non-linear molecular entities compared to the @J03361@, which is due to the odd terms.
2. For linear molecular entities it is the only possible vibronic effect characteristic of degenerate electronic states.
R05290.png
Source:
PAC, 2007, 79, 293. (Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)) on page 414 [Terms] [Paper]