First-principles study on mixed Sin−1N (n=1-19) clusters

The mixed Sin−1N (n=2-19) clusters have been investigated systematically using full-potential linear-muffin-tin-orbital molecular-dynamics (FP-LMTO-MD) method and Amsterdam Density Functional (ADF) program with TZ2P basis set in conjunction with self-consistent field (SCF). Their ionization potentials (IPs), electron affinities (EAs), dipole moments μ, constant volume heat capacity per atom Cv are computed. Based on the Mulliken population analyses, it is found that some of charge is transferred from the Si atoms into the nitrogen atom. Compared with other structures, most of the substitutional structures with three Si-N bonds are more stable. Our calculated results suggest that the N impurity atom improves the stability of the mixed clusters.