SILICON-NIOBIUM BLOCKS FOR THE DESIGNING OF NEW NANOSTRUCTURES

Abstract

Abstract. This paper presents the calculation results of the spatial structure and electron energy spectrum of the anionic silicon-niobium clusters NbSin - (n = 10, 12, 14, 16). A comparison of the calculated total density of electronic states with experimental photoelectron spectra allowed us to determine the structure of the clusters. The calculations were carried out within the density functional theory (DFT) framework where the Becke’s three-parameter and Lee-Yang-Parr’s gradientcorrected correlation hybrid functional (B3LYP) and 6-311+G(d) basis sets were used for the silicon atoms and DGDZVP basis sets were used for the niobium atom for a structural optimization as implemented in GAUSSIAN 09 (G09). The major isomer of the NbSi10 - cluster is a pentagonal bipyramid with a niobium atom in one of the vertices and with four additional silicon atoms. The major isomer of the NbSi12 - cluster is a distorted hexagonal prism with an incapsulated niobium atom. The hexagonal anti-prism isomer and the prolate isomer are also stable. The segment of the prolate isomer are pentagonal bipyramids, with a shared niobium atom at the basis. The major isomer of the 0NbSi14 - cluster is a fullerene-like polyhedron with an encapsulated niobium atom. The prolate isomer of this cluster is also stable, but has a lower average binding energy than prismatic isomers. The major isomer of the NbSi16 - cluster has a fullerene-like structure in the form of a polyhedron with eight pentagonal side edges and rhombic bases. The prolate isomer of this cluster is also stable, but has a lower average binding energy than prismatic isomers. Thus, two types of structures possible for anionic silicon-niobium clusters are endohedral and prolate structures. Endohedral structures are more stable and their calculated electron spectra are more consistent with experimental photoelectron spectra.

Keywords

• DFT
• atomic clusters
• electronic structure
• nanostructures.