Electronic Structure of the Nitrite Ion and Related Species

The performance of a number of wavefunctions based on the molecular orbital and valence bond methods and that of nonpaired spatial orbitals (NPSO) has been examined for the four electrons occupying the π orbitals of the nitrite ion. The related two and three π-electron systems of NO2+ and NO2 have been investigated for the same nuclear arrangement as in the NO2− ion. The performance was judged by calculating (a) the electronic energy; (b) the contributions to this energy from the interelectron repulsion energy and the electron-core energy; (c) the overlap with the corresponding full configuration-interaction function; (d) the charge distribution. It was found that the NPSO method produced the most successful functions. The results have been discussed.