Effect of surface reconstruction on stability and reactivity of Si clusters

Abstract

It is proposed that ``magic number'' Si clusters of intermediate size correspond to structures in which exactly all surface atoms participate in reconstructions similar to bulk-Si surfaces. Models are given for the experimentally observed stable clusters of 33 and 45 atoms, which display features similar to the 7\ifmmode\times\else\texttimes\fi{}7 and 2\ifmmode\times\else\texttimes\fi{}1 reconstructions of the Si(111) surface. The nature of bonding in the energy-optimized atomic geometries is revealed, through first-principles electronic structure calculations, to be covalent.