Structure and electronic property of medium-sized silicon clusters

Abstract The lowest energy structures of Si n ( n = 10 – 20 ) clusters are obtained using the first principles pseudopotential simulated annealing within the local density functional approximation (LDA) implemented in SIESTA method. New low-energy structures are obtained for each cluster size. The Si n clusters generally follow a prolate structures for n 16 and, like spherical structures, with the appearance of an endohedral atom with highly co-ordination starting at n ⩾ 17 . The size dependence of clusters binding energies, and highest-occupied and lowest-unoccupied molecular orbital (HOMO–LUMO) gap are discussed.