Assessment of density functional methods for the calculation of ionizationpotentials of unsaturated molecules

The suitability of density functional (DFT) methods for an accurate determi nation of ionization potentials is the object of a systematic analysis. The studied systems are unsaturated molecules containing 14 and 15 main group elements. The results, which have involved five different functionals, an c ompared to experimental results and to values estimated from calculations p erformed at the Moller-Plesset level up to second order.