Calculated polarizabilities of intermediate-size Si clusters

We have used a first-principles, density-functional-based method to calcula te the electric polarizabilities and dipole moments for several low-energy geometrics of Si clusters in the size range 10 less than or equal to N less than or equal to 20. The polarizability per atom is found to be a slowly v arying, nonmonotonic function of N. Over this size range the polarizability appears to be correlated most strongly to cluster shape and not with eithe r the dipole moment or the highest occupied-lowest unoccupied molecular-orb ital gap. The calculations indicate that the polarizability per atom for Si clusters approaches the bulk limit from above as a function of size. [S105 0-2947(99)07305-9].