ROVIBRONIC VARIATIONAL CALCULATIONS OF THE NITRATE RADICAL

In recent years, sophisticated diabatic Hamiltonians have been developed in order to understand the low-energy vibronic level structure of the nitrate radical (chem{NO_3}), which exhibits strong coupling between the ~{X} and doubly degenerate ~{B} states. Previous studies have reproduced the observed vibronic level positions up to 2000 wn~above the zero-point level, yet the rotational structure has remained uninvestigated with ab initio methods. In this talk, we present calculations of the $Ngeq0$ rovibronic structure of low-lying vibronic states of chem{NO_3}, in which complicated rovibrational and Coriolis interactions have been observed. Our results include calculations using both adiabatic and diabatic Hamiltonians, enabling a direct comparison between the two. We discuss extensions of our treatment to include spin-orbit and spin-rotation effects