STUDY OF TRANSITION-STATE METHODS IN THE CALCULATION OF VERTICAL IONIZATION-POTENTIALS BY LOCAL-DENSITY APPROXIMATION

The vertical ionization potentials of nine small molecules were comput ed by the deMon density functional program and different versions of t he transition-state method and the results were compared with earlier calculations and with experiment. The average absolute deviation of th e 38 computed ionization potentials of the valence electrons of nine s mall molecules from experiment is 0.4 eV, which compares well with pre vious ab initio post-Hartree-Fock and semi-empirical HAM/3 calculation s. The efficient methods were then used to calculate 68 ionization pot entials of sixteen 22-electron molecules, with results of similar qual ity.