A computational investigation of the Ni-doped Si n( n=1−8) clusters by a density functional method

Abstract

The NiSi n ( n=1−8) clusters are investigated computationally using a Density Functional approach. Geometry optimizations of the NiSi n ( n=1−8) units are carried out under the constraint of well-defined symmetries at the B3LYP level employing a pseudopotential method in conjunction with Los Alamos double zeta basis sets. Consequently, the resulting total energies, natural populations, fragmentation energies, and equilibrium geometries of the NiSi n ( n=1−8) clusters are presented and discussed. Theoretical results show that the Ni atom in the small NiSi n clusters absorbs on the surface site, and that the Ni atom in the NiSi 8 cluster prefers being encapsulated into the Si frame. The most stable NiSi n ( n=1, 2) and NiSi n ( n=3−8) clusters correspond to the triplet and singlet spin configurations, respectively. The natural population of the Ni atom in the most stable NiSi n ( n=1−8) clusters varies from positive to negative. The relative stabilities are discussed; the calculated results reveal that the NiSi 8 cluster is the most stable structure.