Nonadiabatic Deactivation of 9<i>H</i>-Adenine: A Comprehensive Picture Based on Mixed Quantum−Classical Dynamics

2008-05-28T00:00:00Z (GMT) by Mario Barbatti Hans Lischka
Mixed quantum−classical dynamics simulations at the multireference configuration interaction (MR-CIS) level were performed for 9<i>H</i>-adenine in order to understand its ultrafast nonradiative decay process. Dynamics simulations were also performed for the model system 6-aminopyrimidine. MR-CIS and complete active space perturbation theory (CASPT2) have been employed to characterize a large variety of qualitatively different conical intersections, the branches of the crossing seam connecting them, and the reaction paths from the Franck−Condon region for 9<i>H</i>-adenine. The results show a two-step process consisting of ultrashort deactivation from S<sub>3</sub> to S<sub>1</sub> and a longer exponential decay step corresponding to the conversion from S<sub>1</sub> to S<sub>0</sub>.