Title: Nonlinear modelling of hierarchical ZnO nanoforms formation

Abstract

The polymorphic transitions of ZnO at the nanoscale was studied from the perspective of stability of polyhedral clusters at the nanoscale. It is shown that in a gaseous environment among cubic, hexagonal prism, spherical, octahedral, icosahedral clusters with primary structures of B3, B4 and B1 in the size range from 7 to 500 atoms only octahedral clusters Zn146O140 and Zn85O80 pass geometry optimisation while approximately preserving the initial crystal structure. These octahedral clusters showed stability for more than 1 ps as a result of molecular dynamics simulations at temperatures from 70 to 1500 K. The PM6 parametrisation method was used for calculations. Due to the compatibility of the [111] plane of a B3 ZnO crystal and the [0001] plane of a B4 ZnO crystal a model of a symmetry-driven transformation at the nanoscale is proposed. An octahedral core provides four tetrahedrally oriented growth plains that define the symmetry of four interconnected ZnO crystals of the B4 polymorphic modification, thermodynamically stable at normal conditions. Defining the transformation area as a formation centre and using nonlinear models of multi element dynamic system self-assembly the formation of hierarchical ZnO nanoforms such as ZnO tetrapods can be described.