Density functional study on structures and electronic properties of NO adsorbed into Pt_mIr_n(m + n = 2-7) clusters

Abstract.

The structure, stability and electronic properties of Pt_mIr_nNO(m + n = 2-7) clusters have been investigated via density functional theory. All ground state structures show an adsorption of NO at the top site of the bare cluster via the N atom. In all of the bimetallic clusters, the NO molecule prefers to be adsorbed near the Ir atom site. The adsorption energy of bimetallic Pt_mIr_nNO ($m+n=2,4,6$) is larger than that of pure clusters with the same cluster size, showing that the interaction of even alloy clusters and NO molecule are stronger. There exist clear even-odd oscillations in the second-order energy difference curves of Pt_mIrNO and PtIr_nNO, indicating that Pt₃IrNO, Pt₅IrNO, PtIr₃NO and PtIr₅NO clusters are more stable than their neighbors. It is obvious that there exist odd-even oscillations in the curves of $m+n=3,4,6$ energy gaps, showing that PtIr₂NO, Pt₃IrNO, PtIr₃NO and Pt₃Ir₃NO clusters are chemically more stable. Magnetic and electronic properties analyses show that the total magnetic moment provided by Ir and Pt atoms, and the magnetic moment mainly arises from localization of the d-electron.