Structural and electronic properties of the adsorption of nitric oxide molecule on copper clusters CuN(N = 1–7): A DFT study

Abstract

The interconversion between different isomers of copper clusters has been investigated using density functional theory. Seven distinct transition states have been located for the isomerization of the Cu3, Cu4, Cu5, Cu6 and Cu7 clusters. The chemisorption of nitric oxide on copper clusters has been studied and the approach of nitric oxide to produce either the nitrosyl (–NO) or the isonitrosyl (–ON) complexes has been compared. The interaction of NO with the copper cluster complexes leads to significant odd–even oscillations of the spin density differences (ΔSD), mean polarizability (α¯) and HOMO-LUMO gaps. The computed binding energies and ionization potentials of the copper clusters are in excellent agreement with the experimental values. The binding energy, charge transfer, forward donation, υ(NO) and bond ellipticity values are higher in the nitrosyl complexes than their isonitrosyl counterparts. The relationship between the ΔSD and the NO stretching frequencies is approximately linear with high correlation coefficients of R2 = 0.94 and 0.96 for nitrosyl and isonitrosyl complexes, respectively. The stable copper clusters have been reoptimized at couple cluster singles and doubles method with Dunning double-ζ basis sets (CCSD/cc-pVDZ level).