Ab initio constructed diabatic surfaces of NO₂ and the photodetachment spectra of its anion

Abstract

A thorough investigation has been performed for electronic structure, topological effect, and nuclear dynamics of NO₂ molecule, where the adiabatic potential energy surfaces (PESs), conical intersections between the ground (X²A₁) and the first excited state (A²B₂), and the corresponding non-adiabatic coupling terms between those states are recalculated to achieve enough accuracy in dynamics. We employ beyond Born-Oppenheimer theory for these two state sub-Hilbert space to carry out adiabatic to diabatic transformation (ADT) to obtain the ADT angles and thereby, to construct single-valued, smooth, and continuous diabatic PESs. The analytic expressions for the adiabatic PESs and ADT angles are provided to represent a two-state three-mode diabatic Hamiltonian of NO₂ for performing nuclear dynamics to calculate the photo-electron spectra of its anion. It appears that not only Jahn-Teller type coupling but also Renner-Teller interaction contributes significantly on the overall spectrum. The coupling between the electronic states ((X²A₁ and A²B₂) of NO₂ is essentially through the asymmetric stretching mode, where the functional form of such interaction is distinctly symmetric and non-linear.