題目：Multi-state ab initio on-the-fly trajectory surface-hopping molecular dynamic simulation for azobenzene photoisomerization
講師：Prof. Chaoyuan ZhuDepartment of Applied Chemistry, National Chiao Tung University
We developed a novel method to simulate analytical nonadiabatic switching probability estimated from electronically adiabatic potential energy surfaces and its gradients along on-the-fly trajectory. The present method can be immediately applied photochemical processes for localized nonadiabatic transitions induced by conical intersection. We could be able to perform on-the-fly trajectory surface hopping at the CASSCF quantum chemistry level to probe nπ* and ππ* azobenzene photoisomerization dynamics within four singlet low-lying electronic states (S0, S1, S2, and S3) coupled with complicated conical intersection network. From cis-to-trans, two-step fast-fast processes have the lifetime from several tenths to hundred femtoseconds, two-step fast-slow and slow-slow processes have lifetime from the several hundreds to thousand femtoseconds. From trans-to-cis, situation is more complicated and slow and fast motions are all mixed up. For trajectories started from S2 state, the all mechanisms dominated by the torsion of CNNC and NNCC moiety, while for trajectories started from S3 state, the mixed torsion of CNNC and inversion of NNC motions were confirmed by the present nonadiabatic molecular dynamics simulation. Quantum yields and lifetimes are all in good agreement with the recent transient absorption spectroscopy experiment.