STUDY OF ELECTRONIC STRUCTURE OF IONS CO2+ AND N20+ BY LCAO-MO-SCF METHOD

Open-shell LCAO-MO-SCF calculations have been carried out on four states of the ion CO2+ and two states of the ion N 2O+, together with closed-shell calculations on the neutral molecules. The process of orbital rearrangement that occurs upon ionization of CO2 and N2O has been studied by means of an atomic population analysis of the calculated wave functions for the neutral molecules and the ions. Ionization of CO2 to the 2II g′;, 2Σu+ and 2Σg+ states of CO2+ is accompanied by a considerable transfer of charge from the carbon to the oxygen atoms via the highly polarizable π electrons, which leads to a weakening of the covalent bonding. Ionization of N2O to the ground state of N2O+ leads to a transfer of charge to the oxygen atom but ionization to the 2Σ+ first excited state of N2O+ involves a transfer of charge towards the other end of the molecule. An attempt was made to correlate variations in the equilibrium bond lengths of the different states of these ions with variations in the bond overlap populations. A satisfactory correlation was obtained for CO2+ using wave functions calculated with a highly flexible basis set.