Theoretical DFT study of the structure and chemical activity of small indium(III) oxide clusters

Abstract

The B3LYP/Lanl2dz and B3LYP/SDD levels of DFT have been used to describe the structural properties of small stoichiometric indium(III) oxide clusters. It was shown that the most stable structures for the monomer and dimer are linear and cubic, respectively, in origin. The most stable trimer is due to the formation of three eight-membered and two six-membered rings with alternation of In and O atoms. Among neutral and monocation tetrameric structures, formation of an “arrowhead” isomer is energetically less favorable than the global minimum structure that has eight six-membered and six four-membered rings. In the pentamer and octamer, a few centers of higher coordination number and a variety of In–O bond lengths are observed. The other centers cannot be fitted to the characteristic bixbyite structure, however, so the larger octamer cannot be a good model for mimicking the properties of the In2O3 crystal structure. An H-terminated cluster model consisting of In13O27H15 is proposed that well describes basic features of indium oxide and tin-doped indium oxide (ITO) structures.