Computational study of the formation of metal-oxide diatomics and clusters

The formation of MO(g)(M = Mn, Fe, Co, Ni) from the atoms, and the condensation of these diatomics to 16-atom and 64-atom clusters with halite-like structures was modelled using an atom superposition–electron delocalisation computational method (which uses a modified extended-Hückel-type Hamiltonian, together with two-body terms to model atomic repulsions). The results show that this model successfully reproduces physical properties, such as energy-level distribution and bulk modulus, of the bulk materials; but is less useful in modelling the energetics of the condensation. Reasons for this are provided through an analysis of the method, and by a comparison with an electrostatic Born model.