Quantum-chemical modeling of F-centers in ionic crystals

A model for quantum-chemical prediction of the electron structure, spectral properties, and reactivity of anion vacancies (F-centers) and their adducts with molecules adsorbed on a surface and in the bulk of ionic broad-band crystals is suggested. Calculations are based on semi-empirical SCF MO LCAO quantum-chemical methods using the Slater AO basis for valence electrons. The crystal electric field effect on the state of an explicitly calculated supermolecule (adsorbed species + F-center) is taken into account at the stage of formation of the backbone Hamiltonian in the SCF MO LCAO method. The F-center is modeled by a five-orbital (n = 1,2) nucleus-free pseudoatom with variable quantum-chemical parameters determined from experimental data for the appropriate crystal.