Photodissociation dynamics of formaldehyde initiated at the T 1/S0 minimum energy crossing configurations

The photodissociation dynamics of H2CO is known to involve electronic states S1 T1 and S0. Recent quasiclassical trajectory (QCT) calculations, in conjunction with experiment, have identified a "roaming" H-atom pathway to the molecular products, H2+CO [Townsend; et al. Science 2004, 306, 1158.]. These calculations were initiated at the global minimum (GM) of S0, which is where the initial wave function is located. The "roaming" mechanism is not seen if trajectories are initiated from the molecular transition state saddle point (SP). In this Letter we identify the minimum energy-crossing configurations and energy of the T1S0 potentials as a step toward studying the multisurface nature of the photodissociation. QCT calculations are initiated at these configurations on a revised potential energy surface and the results are compared to those initiated, as previously, from the S0 GM as well as the S0 SP. The product state distributions of H2 + CO from trajectories initiated at the T1/S0 crossing are in excellent agreement with those initiated at the S0 GM. © 2008 American Chemical Society.

Duke Scholars

Author Peng Zhang Chemistry