Density Functional Study of the Structure and Properties of Cu9 and Cu9(-) .

This work presents a study of the structure of neutral and anionic copper cluster nonamers with density functional theory calculations. The structure optimization and frequency analysis were performed at the local density approximation (LDA) level of theory with the exchange correlation functional by Vosko, Wilk, and Nusair (VWN). Improved calculations for the structure stability were based on the generalized gradient approximation (GGA) where the exchange correlation functional of Perdew and Wang (PW) was used. For both neutral and anionic clusters, new isomers are found that are more stable than those already presented in the literature. Adiabatic and vertical electron affinities are calculated and compared with the experimental value reported for Cu9. The calculated values are in good agreement with the available experimental data. An analysis of the most relevant molecular orbitals (MOs) of the low-lying neutral and anionic copper cluster nonamers is reported, too.