The angular overlap model, an attempt to revive the ligand field approaches

Abstract

A general method for the calculation of orbital energy differences within a partially filled l-shell of a central ion in an inorganic chromophore is described. The angular overlap model covers σ, π and δ anti-bonding (as well as bonding) effects, and it is shown that the consequence of the model is identical with that of a singular contact term potential acting close to each ligand nucleus. Because of this the model can also treat chromophores containing different ligands, each new ligand contributing one σ and one π (and one δ) radial parameter. In this way fewer parameters are involved than in usual ligand field approaches. Selected symmetries of chromophores, cubic, pentagonal, tetragonal, and trigonal, are used to illustrate the applications of the model.