Calculation of vertical ionization potentials of hydrogen peroxide by perturbation corrections to Koopmans' theorem

Vertical ionization potentials (VIP's) of hydrogen peroxide are calculated by perturbation corrections to Koopmans' theorem and its conformation is investigated on the basis of the calculated VIP's. The calculated VIP's compare well with the observed values. The analysis based on the VIP's gives a reasonable conformation, although the energy-optimizing procedure cannot reproduce the skew conformation. The lone pair – lone pair interactions are also discussed.