Comprehensive understanding of size‐, shape‐, and composition‐dependent polarizabilities of SimCn (m, n = 1–4) clusters

Abstract

AbstractWe performed a comprehensive study of the size‐, shape‐, and composition‐dependent polarizabilities of SimCn (m, n = 1–4) clusters on the basis of the density‐functional‐based coupled perturbed Hartree–Fock calculations. We found better correlations between the polarizabilities and both the binding energies (Eb) and change in charge distribution (Δq) than the energy gaps. The α values exhibit overall decreasing and increasing trends with increases in the Eb and Δq values, respectively. For isomers with the same Eb values and different polarizabilities, Δq can well explain the difference in polarizabilities. The π‐electron delocalization effect is the best factor for understanding the shape‐dependence. For a given m/n value, the linear clusters have an obviously larger polarizability than both the prolate and compact clusters, irrespective of the cluster size. We fit a quantitative expression [α = A − (A − B) × exp(−k(m/n))] to describe the composition‐dependent polarizabilities. © 2012 Wiley Periodicals, Inc.