Non adiabatic dynamics of photoexcited cyclobutanone: predicting structural measurements from trajectory surface hopping with XMS-CASPT2 simulations

Abstract: For years, theoretical calculations and scalable computer simulations have complemented ultrafast experiments as they offer the advantage to overcome experimental restrictions and have access to the whole dynamics. This synergy between theory and experiment promises to yield a deeper understanding of photochemical processes, offering valuable insights into the behavior of complex systems at the molecular level. However, the capacity of theoretical models to predict ultrafast experimental outcomes has remained largely unexplored. In this work, we aim to predict the electron diffraction signals of an upcoming ultrafast photochemical experiment using high-level electronic structure calculations and non adiabatic dynamics simulations. In particular, we perform trajectory surface hopping with XMSCASPT2 simulations for understanding mechanistic photodissociation of cyclobutanone upon excitation at 200 nm.