Regular Article THE EUROPEAN PHYSICAL JOURNAL D Activated adsorption of CO on yttrium clusters

Abstract. Calculations based on density-functional theory show that COYn (n = 2–13) clusters have large adsorption energy, a small HOMO-LUMO gap, lengthening C-O bond and weak vibrational frequency between C and O atoms. It was found that the basic framework of the host Yn clusters remains invariable in most cases, but adsorbing CO can induce significant alteration of the structures of corresponding Yn clusters with n = 5, 7, and 8. Both the C and O atom are seen to bond with Y atoms simultaneously. COY5 and COY8 exhibit high stability which can be interpreted in terms of the sp 3 hybridization of the C atom. The interaction between Y and O atoms plays an important role in terms of the stability of COYn series. The magnetic moments of host Yn clusters are mostly weakened where both C and O atoms exhibit slight ferrimagnetic ordering. COY6 has the smallest value of adsorption energy, second differences of total energy, fragmentation energy, HOMO-LUMO gap, but relatively large magnetic moment (6µB) with the exhibition of ferromagnetic coupling of C and O atoms.