A DFT based ligand field model for magnetic exchange coupling in transition metal dimer complexes:: (ii) application to magnetic systems with more than one unpaired electron per site

The DFT based ligand field model for magnetic exchange coupling proposed recently, has been extended to systems containing more than one unpaired electron per site. The guidelines for this extension are described using a model example – the complex (NH3)3CrIII(OH)3CrIII (NH3)33+. The exchange Hamiltonian, Hex=−J12S1S2 has been simplified using symmetry principles, i.e. utilizing the D3h(C3v) CrIII – dimer(site) symmetry. Both antiferro- and ferromagnetic exchange coupling constants are found to yield important contributions to the value of the (negative, antiferromagnetic) exchange coupling constant in good agreement with experiment.