Vibronic Interactions in the Photoelectron Spectra\nof CAl<sub>3</sub>Ge<sup>–</sup>: A Theoretical Study

This\nstudy probes the vibronic interactions in the photoelectron\nspectra of CAl<sub>3</sub>Ge<sup>–</sup>, exploring its six\nexcited electronic states through an approach that combines the <i>ab initio</i> electronic structure calculations and the quantum\nnuclear dynamics. Central to this investigation is utilizing a model\ndiabatic Hamiltonian, which allows for the exact evaluation of Hamiltonian\nparameters and fitting potential energy cuts (PECs). Notably, the\nanalysis of these PECs uncovers pronounced nonadiabatic effects within\nthe photoelectron spectra, emphasized by the presence of multiple\nconical intersections. The investigation of nuclear dynamics, with\nand without the same spatial symmetry coupling, is achieved by employing\ntime-dependent (TD) and time-independent (TI) quantum mechanical methods.\nThese nuclear dynamical studies effectively simulated all the photoelectron\nspectral bands. Eventually, the theoretical findings conformed well\nwith available experimental observations, highlighting the nonadiabatic\neffects among the closely situated spectral bands.