SCF Determination of the Ground and Excited States of NO2

LCAO–MO–SCF wavefunctions have been determined for the ground and five excited states of NO2 at five different ONO angles. Molecular electronic configurations for the X̃, Ã, and B̃ states have been assigned on the basis of the calculated vertical excitation energies and speculations for those of the C̃, D, G, Ĩ, and J̃ states are made. The G̃ state is predicted to be B12 with a smaller equilibrium angle and considerably different value of R from the ground state. Estimates of correlation energy changes suggest that they are probably unimportant for most of the NO2 spectrum. The qualitative changes in orbital one-electron energies with angle agree with those reported by others for AB2 systems. Two closely related interpretations of geometry changes upon excitation are given, one based upon population analyses, the other on the AB2 correlation diagram.