New insights into the effects of covalency on the ligand field parameters: a DFT study

A new, non-empirical, DFT based ligand field (LF) model is proposed. The calculation involves two steps: (i) an average of configuration (AOC), with equal occupation of the d-orbitals is carried out, (ii) with these Kohn-Sham orbitals kept frozen, the energies of all single determinants (SD) within the whole LF-manyfold is performed. These energies are then used to estimate all the Racah- and LF-parameters needed in a conventional LF-calculation. The results of this first-principle prediction are in very good agreement with the experimental values. Test calculation of tetrahedral Cr-(IV) and Ni-(II) complexes are used to validate the new model and to analyze the parameters of the LF. (C) 2002 Elsevier Science B.V. All rights reserved.