Nonadiabatic wave packet dynamics on the coupled X˜²A₁/òB₂ electronic states of NO₂ based on new ab initio potential energy surfaces

Abstract

We report new accurate ab initio potential energy surfaces (PESs) for the ground (X˜²A₁) and first excited (òB₂) electronic states of NO₂. The adiabatic potential energy data are calculated by the configuration-selecting multi-reference configuration-interaction method employing the cc-pVTZ basis set. We diabatize the adiabatic potential energy data and investigate the nuclear dynamics on these coupled electronic states by a time-dependent wave packet method. First, we investigate the photodetachment spectrum of NO₂^- for a transition to the òB₂ state and compare our findings with the available experimental results. The agreement is very satisfactory. In addition, we examine the femtosecond decay of the òB₂ diabatic electronic population revealing the impact of the nonadiabatic coupling on the time-dependent dynamics (internal conversion process) of NO₂. The present study based on more accurate ab initio PESs enables us to confirm our earlier estimate of the vibronic coupling strength near the energetic minimum of the X˜²A₁/òB₂ crossing seam.