Multimode Jahn-Teller and pseudo-Jahn-Teller interactions in the cyclopropane radical cation: complex vibronic spectra and nonradiative decay dynamics.

TLDR: The vibronic level spectra and the ultrafast nonradiative decay of the excited cationic states are examined and are related to the highly complex entanglement of electronic and nuclear degrees of freedom in this prototypical molecular system.

Abstract: The complex vibronic spectra and the nonradiative decay dynamics of the cyclopropane radical cation (CP+) are simulated theoretically with the aid of a time-dependent wave packet propagation approach using the multireference time-dependent Hartree scheme. The theoretical results are compared with the experimental photoelectron spectrum of cyclopropane. The ground and first excited electronic states of CP+ are of X2E‘ and A2E‘ ‘ type, respectively. Each of these degenerate electronic states undergoes Jahn−Teller (JT) splitting when the radical cation is distorted along the degenerate vibrational modes of e‘ symmetry. The JT split components of these two electronic states can also undergo pseudo-Jahn−Teller (PJT)-type crossings via the vibrational modes of e‘ ‘, and symmetries. These lead to the possibility of multiple multidimensional conical intersections and highly nonadiabatic nuclear motions in these coupled manifolds of electronic states. In a previous publication [J. Phys. Chem. A 2004, 108, 2256], ...