DFT and CI Studies of Electronic Structure and Photoionization of Sc, Ti, V, Cr, and Co Tris-β-diketonate Complexes

Abstract

Orbital structure calculations were performed in the density functional theory (DFT) approximation for neutral complexes of Sc, Ti, V, Cr, and Co tris-β-diketonates; for the first three compounds, the structures of the ground ionic states and ionization energies were calculated in the CI approximation with decomposition on the orbitals of DFT. The sequence of the highest occupied orbitals found by this procedure coincides with the order of bands in the PES spectrum, while in the SCF-HF ab initio method, it does not. After the electron removal, all orbitals are stabilized by about 4.5 eV; for the vanadium complex, the removal of one d electron leads to the greatest stabilization of the remaining occupied orbital, which is essentially a d orbital. In CI calculations, using the DFT orbitals for decomposition does not lead to significantly better agreement with experiment when compared to the single-determinantal approximation and to the CI method with orbitals of the ab initio approximation.