Computer simulation of the tension of noncrystalline silicon nanoparticles

Abstract

Vitreous and amorphous silicon nanoparticles consisting of 500 atoms are investigated using the molecular dynamics method after a series of uniform tensions with a total tensile strain Δl/l ≈ 0.10 and subsequent relaxation. The disappearance of the second peak in the radial distribution function for an amorphous nanoparticle subjected to a uniform tension with a tensile strain Δl/l ≈ 0.06 indicates the destruction of the tetrahedral packing. In nanoparticles of both types, the energetically most favorable atomic packing is retained in middle layers for all the strains under investigation. The distribution of Si-Si bond lengths and the larger mean number of bonds per atom suggest that the structure of the vitreous nanoparticle is characterized by a higher statistical resistance to tension. This nanoparticle also has a higher kinetic resistance to uniform tension. Unlike the amorphous nanoparticle, the radial component of the coefficient of mobility of atoms in the vitreous nanoparticle neither dominates over its tangential component nor increases regularly in going from the center of mass of the nanoparticle toward the nanoparticle surface. As the number of tensions increases, the mean length of Si-Si bonds decreases in the vitreous nanoparticle and, by contrast, increases in the amorphous nanoparticle.