Optical properties of silver and copper clusters with up to 150 atoms

Optical absorption spectra of the lowest-energy structures of small and medium-sized transition-metal clusters, AgN and CuN with N up to 150, are investigated within the classical Mie–Gans theory. The global-minima structures of these clusters have been determined in our previous studies using an unbiased structure-optimization approach combined with the embedded-atom total-energy method. The influence of cluster size, shape and metal on the peak positions and the relative intensities in the absorption spectra is studied systematically. Our studies give information on differences/similarities between optical absorption spectra of different metal clusters and their isomers. The main features of the obtained optical spectra for silver clusters are in good agreement with the available experiments and with results of the computationally much more advanced TDDFT calculations.