THE ESTIMATIONS OF INNER-SHELL IONIZATION ENERGIES FOR ALKYL HALIDES: A DESIGNATED SINGLE-CONFIGURATION CASSCF APPROACH AND ADVANCED CORRECTION

Abstract

Based on the Franck–Condon principle, vertical ionization energies regarding the inner-shell valence electrons of alkyl halides and their unsaturated analogues were evaluated with a designated single-configuration complete active self-consistent field (CASSCF) approach as well as the advanced correction with configuration interaction. Excitations corresponding to the elimination of one electron from a specific molecular orbital of these species were calculated by the deviation between the energy of the SCF-optimized neutral structure and of its cation. The freezing over the outer orbitals with identical symmetry was achieved while performing the CASSCF ionization calculation for the inner orbitals. These energy evaluations utilized Pople's 6-31G*, 6-311G** and Roos' ANO basis sets. Computed results agreed well with the experimental data. The characters for the molecular orbitals of corresponding vertical ionizations could be qualitatively assigned by the MOLDEN visualization program.