Non-adiabatic dynamics of the highly excited uracil cation*

Conical intersections facilitating non-adiabatic transitions have been found to play a key role in many photo-physical pathways. Radical cations of nuclear acid bases involved in charge transfer processes in DNA exhibit ultrafast dynamics governed by the existence of non-adiabatic couplings between excited states, where electron-nuclei coupled dynamics become important. We investigate the dynamics of the uracil cation, using highly-accurate coupled electron-ion dynamics methods and compare the results with more commonly used and less computationally intensive methods. In particular, trajectory-based surface hopping dynamics has proven to be a powerful tool to study coupled nuclear-electronic dynamics, but it does not properly account for quantum decoherence. Instead, a new coupled-trajectory approach has been proposed based on the exact electron-nuclear correlation from the exact factorization of a full molecular wave function. Numerical simulations with model systems have shown that the electron−nuclear coupling beyond the non adiabatic coupling terms can describe the quantum coherence properly. Within this method the quantum (de)-coherence in large molecules can be treated correctly at the same computational cost as the original surface hopping dynamics.