Vibronic coupling effects in the photoelectron spectra of LiB6−

Abstract

This present article exhibits a theoretical exploration of vibronic coupling effects in the 193 nm experimental photoelectron spectra of LiB₆⁻, focusing on its six lowest-lying electronic states. Based on the adiabatic potential energy curves derived from ab initio calculations, we construct a diabatic vibronic Hamiltonian and perform nuclear dynamics calculations by adopting TD and TI formulations of quantum mechanics, considering adiabatic (uncoupled) and non-adiabatic (coupled) scenarios. In this study, Poisson statistics provided vibronic intensity progressions from an adiabatic perspective, and the rapid transfer of electronic population confirmed the magnitude of the non-adiabatic coupling. Our final simulated spectrum reproduces the peaks of the experimental spectrum with good agreement, enabling detailed vibronic interpretation of the photoelectron spectrum of LiB₆⁻.