Vibronic Coupling in Spherically Encapsulated, Diatomic Molecules: Prediction of a Renner-Teller-like Effect for Endofullerenes

In the year 1933, Herzberg and Teller realized that the potential energy surface of a triatomic, linear molecule splits into two as soon as the molecule is bent. The phenomenon, later dubbed the Renner-Teller effect due to the detailed follow-up work of Renner on the subject, describes the coupling of a symmetry-reducing molecular vibration with degenerate electronic states. In this article, we show that a very similar type of nonadiabatic coupling can occur for certain translational degrees of freedom of diatomic, electronically degenerate molecules when trapped in a nearly spherical or cylindrical quantum confinement, e.g., realized through electromagnetic fields or molecular encapsulation. We illustrate this on the example of fullereneencapsulated nitric oxide, and provide a prediction of its interesting, perturbed vibronic spectrum.

Automated summary

This article explores the occurrence of nonadiabatic coupling for certain translational degrees of freedom of diatomic, electronically degenerate molecules trapped in nearly spherical or cylindrical quantum confinement. The example of fullerene-encapsulated nitric oxide is used to illustrate this phenomenon and predict its perturbed vibronic spectrum.