Ab initioCalculations for the Polarizabilities of Small Semiconductor Clusters

Polarizabilities of small Siₙ, Geₙ ( n≤10), and GaₙAsₘ ( n+m≤8) clusters are calculated using the higher-order finite-difference pseudopotential method in real space. We find the polarizabilities of the clusters considered to be higher than the value estimated from the ``hard sphere'' model using the bulk static dielectric constant. The computed polarizabilities per atom tend to decrease with increasing the cluster size. This trend resembles the case of metallic clusters, for which the bulk limit is approached from above, and confirms the ``metalliclike'' nature of small semiconductor clusters.