【摘 要】
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In this article,structures and energies of cyclopropenone in the low-lying electronic states have been determined by the CASSCF and MS-CASPT2 calculations with different basis sets.Two minimum-energy
【机 构】
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Key Laboratory of Theoretical and Computational Photochemistry Ministry of Education College of Chem
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In this article,structures and energies of cyclopropenone in the low-lying electronic states have been determined by the CASSCF and MS-CASPT2 calculations with different basis sets.Two minimum-energy conical intersections(CI-1 and CI-2)between S0 and S1 were obtained and their topographic characters were characterized by the SA4-CAS(10,9)calculated energy gradients and non-adiabatic coupling vectors.The AIMS method was used to carry out non-adiabatic dynamics simulation with ab initio calculation performed at the SA4-CAS(10,9)level.Based on time evolution of wave functions simulated here,the S1 lifetime is fitted to be 125 fs with a pure exponential decay for the S1 electronic population.The CI-1 intersection is mainly responsible for ultrafast S1→S0 non-adiabatic transition and the photo-induced decarbonylation is a sequential process,where the first C-C bond is broken in the S1 state and fission of the second C-C bond occurs in the S0 state as a result of the S1→S0 internal conversion via the CI-1 region.As a minor channel through the CI-2 region,the decarbonylation proceeds in an asynchronous concerted way.Effects of the S1 excess energies and the S1-S0 energy gap on the non-adiabatic dynamics were examined,which reveals that the S1→S0 non-adiabatic transition occurs within a small energy gap and high-energy conical intersection regions can play an important role.The present study provides new insights into mechanistic photochemistry of cyclopropenones and reveals that the AIMS dynamics simulation at a high-accuracy ab initio level is a powerful tool for exploring a mechanism of an ultrafast photochemical reaction.
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