First principle study on SimNm and SimNm±1 (m = 2–10) clusters

The mixed SimNm and SimNm±1 (m = 2–10) clusters are investigated systematically using Amsterdam Density Functional (ADF) program with TZ2P basis set in conjunction with self-consistent field (SCF). The total binding energy, dipole moments, energy gap between the HOMO (highest-occupied molecular orbital)–LUMO (lowest-unoccupied molecular orbital) and constant volume heat capacity of these clusters are computed. Calculation results show the structures of these clusters evolve from linear to planar and three dimensions as the atom number increases. The N dimer can easily form and escape from N-rich clusters, whose physical properties are dominated by the remaining parts. Mulliken population analyses indicate partial charge transfer from silicon to nitrogen atoms.