The nonradiative decay of a n-stacked pair of adenine molecules, one of which was excited by an ultrafast laser pulse, is studied by semiclassical dynamics simulations. This simulation investigation is focused on the effect of the formation of bonded excimer in stacked adenines on the mechanism of ultrafast decay. The simulation finds that the formation of the bond- ed excimer significantly lowers the energy gap between the LUMO and HOMO and consequently facilitates the deactivation of the electronically excited molecule. On the other hand, the formation of the chemical bond between two stacked adenines re- stricts the deformation vibration of the pyrimidine of the excited molecule due to the steric effect. This slows down the formation of the coupling between the HOMO and LUMO energy levels and therefore delays the deactivation process of the excited adenine molecule to the electronic ground state.
DOU YuShengZHAO WenHuiYUAN ShuaiZHANG WenYingTANG Hong
The photochromic ring-opening reaction of spiropyran（SP） has been investigated by a realistic semiclassical dynamics simulation,accompanied by SA3-CASSCF（12 10）/MS-CASPT2 potential energy curves（PECs） of S0–S2.The main simulation results show the dominate pathway corresponds to the ringopening process of trans-SP to form the most stable merocyanine（MC） product.These findings provide more important complementarity for interpreting experimental observations.
