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Theoretical investigation of the nonadiabatic deactivation of pyrrole

Mixed quantum− classical dynamics simulations at the multireference configuration interaction (MR- CISD) level of theory were performed for pyrrole in order to understand its ultrafast nonradiative decay process. The results of previous studies by Sobolewski and coworkers have shown that deactivation occurs via NH stretching mechanism [1, 2]. Recently, we found that this process corresponds to 85 % of calculated trajectories, while 15 % of deactivation mechanism involves out- of plane ring deformation [3, 4]. More detailed analysis indicated that the first step of a deactivation process corresponds to the decay of molecules from S4 to S1 state. This process is very fast and it takes only 44 fs. The second step corresponds to a deactivation from S1 to the ground state and it requires 80 fs. The role of conical intersections in a deactivation process will be discussed in some detail.

pyrrole; conical intersection; nonadiabatic dynamics; multireference calculations

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