Ab initio study of the photodissociation of HCO in the first absorption band: Three-dimensional wave packet calculations including the X2A′−Ã2A″ Renner–Teller coupling

We present a comprehensive investigation of the Renner–Teller induced dissociation of HCO(Ã) following excitation in the first absorption band (Ã2A″←X̃2A′). The dynamics calculations are performed in the time-dependent picture by propagating two coupled wave packets including all three internal degrees of freedom. The corresponding potential energy surfaces have been generated from new electronic structure calculations. The quantities of interest are (i) the vibronic excitation energies in the Ã2A″ state, (ii) the state- and K-dependent lifetimes of the rovibronic states in the excited manifold, and (iii) the final vibrational–rotational state distributions of the fragment CO molecule. In all cases very satisfactory agreement with recent experimental results obtained from photofragment yield spectroscopy is achieved.