Structures of SinHm clusters in neutral, positive and double positive charge states have been calculated by nonconventional tight-binding method and molecular dynamics. An influence of the charge state and the termination by hydrogen of dangling bonds on cluster structures those are obtained as a result of chemical vapor precipitation in silane, is considered for the first time. Fully hydrogenated clusters have tetrahedral branched structures. Other isomers have forms of closed circles.

Bare silicon clusters with non-diamond and diamond-core structures, as well as silicon-hydrogen clusters, were simulated using a recently developed non-conventional tight-binding molecular-dynamics method. In the range of cluster sizes considered (≤ 71 atoms), clusters with a diamond core were found to be energetically unfavorable compared to representative non-diamond clusters from a regular, one-dimensional growth pattern, proposed by the authors. It is shown that the method used here can reproduce the results of high-level ab initio methods including multi-level multistep methods such as G3/B3LYP.

Выходные данные статьи и справка о публикации: в день оплаты статьи Рассылка печатных журналов и оттисков: 05.03.2022

Stability and charge states of vacancy in Si29 and Si38 clusters have been calculated by non-conventional tight-binding method and molecular dynamics. Based on the theoretical calculations, it was shown that the vacancy in pure dimerized clusters is unstable, while in hydrogenated Si29H24 and Si38H30 clusters it is stable, but leads to a distortion of its central part with the transition of symmetry from Td to C3v and a change in the forbidden gap. The charges of cluster atoms in the presence of a vacancy are distributed so that all silicon atoms acquire a stable negative charge, which occurs due to the outflow of electrons of the central atom to the neighboring spheres.

The specific properties of tubular and fullerenlike silicon nanoparticles depend on theirs electronic structure, which is directly related to the surface geometry. Using density functional approach, a novel dual nature of the surface structure of silicon nanotubes which depends on the type of nanotube have been revevaled. The rippled form of the surface has shown to be a favorable one for (n, n) type structure and the most stable form for (n, 0) Si NT is the nanotube with a smooth-walled graphene-like surface. The phenomenon is explained by the relative position of the non-hybridized p orbitals on the surface.