On-the-Fly Nonadiabatic Molecular Dynamics Reveals Dissociation Mechanisms of Multiply Charged Molecules

Understanding the dissociation of multiply charged molecules is crucial yet challenging due to complex multibody correlations and nonadiabatic dynamics. Conventional ab initio molecular dynamics simulations commonly struggle to capture excited electronic states and intricate electron-nuclear coupling, particularly in distinguishing sequential and nonsequential dissociation pathways. To address these limitations, we present a combined theoretical and experimental study on the dissociation mechanisms of CO₂³⁺. Our approach employs on-the-fly nonadiabatic molecular dynamics simulations, utilizing Dalitz plots and Newton diagrams to differentiate dissociation channels. The simulations reproduce the key dynamical signatures observed via a COLTRIMS reaction microscope, enabling the state-resolved disentanglement of overlapping spectral features. This Letter provides mechanistic insights into the fragmentation dynamics, refining the interpretation of experimental data and offering an in-depth understanding of nonadiabatic molecular dynamics.