We propose a structure of the ${\mathrm{Si}}_{45}$ cluster through extensive search. This structure consists of two cages, where the outer cage contains threefold-, fourfold-, and fivefold-coordinated atoms. Our calculated local density of states of atoms in a concerned Si isomer shows that both threefold-coordinated Si atoms and fourfold-coordinated Si atoms with a back-bond are all active sites in the outer cage of this isomer. Especially, the number of the dangling-bond atoms in the outer cage of our lowest-energy isomer is significantly less than those of any previous structure for ${\mathrm{Si}}_{45}$ clusters. Therefore, our obtained lowest-energy structure of the ${\mathrm{Si}}_{45}$ cluster is a highly desirable candidate to serve as the lowest reactivity for the ${\mathrm{Si}}_{45}$ cluster.

• Received 9 July 2005

DOI:https://doi.org/10.1103/PhysRevB.73.045417