Simulation of the photodeactivation of formamide in the n_o-pi* and pi-pi* states:An ab initio on-the-fly surface-hopping dynamics study

摘要

The short-time photodynamics (1 ps) of formamide in its low-lying singlet excited n_O-pi* and pi-pi states have been investigated by the direct trajectory surface-hopping method based on multiconfigurational ab initio calculations.The simulations showed that in both states,the primary deactivation process is C-N bond dissociation.In the ground state,the energy is transferred to (a) translational motion of the HCO and NH2 fragments,(b) additional C-H dissociation from the vibrationally hot HCO fragment,or (c) formation of NH3 and CO.In addition to the C-N dissociation pathway,C-O bond fission is found to be an additional primary deactivation path in the pi-pi dynamics.From fractional occupations of trajectories,lifetimes of formamide were estimated:tau(S1)=441 fs and tau(S2)=66 fs.