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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

The short-time photodynamics (1 ps) of formamide in its low-lying singlet excited nO-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: (S1)=441 fs and (S2)=66 fs.

formamide photochemistry ; dynamics syimulations ; surface hopping method ; ab initio calculations

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