Statistical analysis of interatomic bonds and interlayer distances in a carbon helical onion structure with a variable step

A model of the atomic configuration of a helically twisted carbon nanocluster is optimized by combined methods of classical molecular dynamics and density functional. It is shown that, as a result of optimization, a layered helical structure is formed with a variable interlayer distance increasing from the center of the cluster to its periphery. The optimized structure was used for calculating the valence angle and interturn distribution functions. It is also shown that the model of a helical structure with a variable step describes with a sufficient accuracy the experimental dependences of interlayer distances on the radius of onion structures known from the literature and obtained by processing of high-resolution electron microscopy images of carbon onion structures.