Knowledge Bank

Koopmans’ Theorem is used to determine energy levels and orbital characteristics for the lowest members of s,p,d,f,g,h Rydberg series in $CO2$. The energy levels are in good agreement with results of SCF calculations and experimental energy levels. It appears that unambiguous spectral assignments can be based upon the comparison of ab initio and observed energy levels in the case of penetrating Rydberg orbits. The energy levels associated with the higher angular momentum orbits exhibit degeneracies and separations which more closely approximate those of the hydrogen atom.