Vibronic Interactions in the Photoelectron Spectra of CAl₃Ge^–: A Theoretical Study

This study probes the vibronic interactions in the photoelectron spectra of CAl₃Ge^-, exploring its six excited electronic states through an approach that combines the <i>ab initio</i> electronic structure calculations and the quantum nuclear dynamics. Central to this investigation is utilizing a model diabatic Hamiltonian, which allows for the exact evaluation of Hamiltonian parameters and fitting potential energy cuts (PECs). Notably, the analysis of these PECs uncovers pronounced nonadiabatic effects within the photoelectron spectra, emphasized by the presence of multiple conical intersections. The investigation of nuclear dynamics, with and without the same spatial symmetry coupling, is achieved by employing time-dependent (TD) and time-independent (TI) quantum mechanical methods. These nuclear dynamical studies effectively simulated all the photoelectron spectral bands. Eventually, the theoretical findings conformed well with available experimental observations, highlighting the nonadiabatic effects among the closely situated spectral bands.