Comparison between stability, electronic and structural properties of noble metal nanoclusters

Density functional theory (DFT) calculations are carried out to study the electronic, structural, and stability properties of noble metal nanoclusters. Size-dependent properties of copper, silver, and gold nanoclusters are calculated and compared in the size range below 2 nm. Interband transition energy, formation energy, HOMO–LUMO energy gap, and surface charge density properties of the noble metal clusters are investigated. Noble metal nanoclusters that are investigated in this research have a non-zero energy gap, which indicates a non-metallic character. The formation energies decrease by increasing the size of the clusters. The calculated formation energies are compared with bulk experimental cohesive energies. The trend of reduction in formation energy is consistent with experimental results. The calculated interband transition energies of noble metals reduce by increasing the size of the nanoclusters and are in agreement with the experimental results. Finally, we calculate and compare surface charge density of different noble metals. The calculated surface charge density can explain the experimental results of vanishing of localized surface plasmon resonance with decreasing size in the case of copper clusters, with respect to gold clusters for sizes <2 nm.