Dynamics and spectroscopy of CH2OO excited electronic states. Issue 16 (4th April 2016) - Kalinowski, Jaroslaw
Abstract : Ab initio molecular dynamics with a high level of theory is used to explore the fate of a Criegee intermediate after an initial electronic excitation. Results are confronted with experiments. Abstract : The excited states of the Criegee intermediate CH2 OO are studied in molecular dynamics simulations using directly potentials from multi-reference perturbation theory (MR-PT2). The photoexcitation of the species is simulated, and trajectories are propagated in time on the excited state. Some of the photoexcitation events lead to direct fragmentation of the molecule, but other trajectories describe at least several vibrations in the excited state, that may terminate by relaxation to the ground electronic state. Limits on the role of non-adiabatic contributions to the process are estimated by two different simulations, one that forces surface-hopping at potential crossings, and another that ignores surface hopping altogether. The effect of non-adiabatic transitions is found to be small. Spectroscopic implications and consequences for the interpretation of experimental results are discussed.