Density-functional studies of plasmons in small metal clusters.

We study the formation of plasmon modes of small gold clusters by modeling the excitation spectra. The shape change of the longitudinal mode as a function of cluster size is studied using time-dependent Kohn-Sham theory and Gaussian basis sets. The presence of d electrons in gold atoms affect the plasmon formation process, resulting in a high excitation energy for transverse mode and a complicated spectra profile in general. The transverse mode can still be identified with the help of a frozen-orbital approximation.