ABINITIO CHARACTERIZATION OF SEVERAL STATES OF NITROXYLIUM (NO3+) - COMPARISON OF FRAGMENTATION ENERGIES OF NITROXYLIUM, NITROXYL (NO3), AND NITRATE

Ab initio calculations have been performed at the self-consistent field (HF) level, and its perturbative extensions up to fourth-order (MPn), for several electronic states of nitroxylium (NO3+) as well as for a large number of reference species. Geometries are optimized at the HF/DZ and HF/DZP levels (double zeta and double zeta plus polarization bases). The ground state is found to be the D3h 1A1' state, with the C2-upsilon 1A1 (closed Y) state higher by 0.94 eV. The relationship between adding electrons or oxygen atoms to NO+ and NO2+ is explored, especially in relation to fragmentation energies of NO3 +/- q (q = 0 or 1). A comparison is drawn between NO3+ and two isoelectronic species, CO3 and C(CH2)3, where no surprises are found.