Oxygen locations and electronic structures of oxygenated coinage-metal clusters

Abstract

Abstract The structure features and stability of MnO (M = Cu, Ag and Au; n = 2–9) clusters are investigated using the genetic algorithm combined with the density functional theory (DFT). It is found that CunO and AgnO are more inclined to 3-dimension compact structures, while the transition of AunO from 2 to 3-dimensions occurs at n = 7, in which O atoms prefer to be located on the vertexes regardless of different sizes and configurations of metal Mn cores. Due to the relativistic effect, the stability of AunO is maximum, while the AgnO are less stable, and that of CunO is in between them. The molecular dynamics simulations show that the structures of M4O can maintain integrity with only slight disturbances of individual atoms at a temperature of 300 K. But only the Au4O is stable at 500K, and the Ag4O and Cu4O have severely structural deformation. In most cases, the density of states of larger-sized MnO can be regarded as the superposition of small clusters, and distributions of the curves are in good agreement on the whole. The molecular orbitals reveal that the HOMO/LUMO orbitals are mainly distributed around the M atoms. The natural population analysis charges show that the charge-transferring direction is from M to O atoms, where the charge of O atoms exhibits odd–even oscillation behaviors, with different intensity peaks at the same n.