Otimizações de modelos de nanotubos de ZnO nas formas armchair e zigzag

Abstract

The zinc oxide nanotubes are structures with wide applicability in nanoscience being used in biosensors as a glucose sensor, have semiconducting properties, piezoelectric, optical, and catalytic applications as well as the gas sensor varistors due to their electronic properties and structural. Therefore, the study of nanostructure grown recently, as well as its applicability in the development of new nanoscale materials. In this study were analyzed in the nanotubes zinc oxide single-walled shaped and zigzag armchair, behavior of the energy in the process of optimization as well as the energy change, was diagnosed with the energy required for the winding of a nanotube. Analyzes were also made of | HOMOLUMO | for some structures by making comparisons with the | HOMO-LUMO | for flat structures. A study was made of the rate of change of load on each level and the variation of the dipole. Were also observed, the distances between oxygen-oxygen-zinc and zinc, analysis of the bond angles, and torsion. For these studies we used the semi-empirical methods AM1, MNDO and Ab Initio Hartree Fock bases with 3-21G and HUZINAGA. The objective of these studies is to obtain data related to nanotubes of zinc oxide that can assist in understanding the behavior of these structures and their potential applicability in the construction of new nano materials. It was observed that the structures as armchair were more stable, seeking a lower energy conformation compared with the zigzag-shaped structures. The structures obtained in the form of a zigzag | HOMO-LUMO | values less than 5.5 eV. which is characteristic of semi-conductors, the same was not observed in the structures that had armchair | HOMO-LUMO | values greater than 5.5 eV. which is characteristic of insulating materials, was also calculated dipole moment of some structures as well as the total amount of load per level by comparing the structures with opposite chirality. In relation to the distances and diameters of connections was observed that the armchair structures vary more in search of the conformation of lowest energy. In the zigzag-shaped structures suffer less variation of the link distance and diameter in most cases lost symmetry when subjected to the optimization process. For bond angles, and torsion, the armchair structure with the same number of levels, showed variations similar behavior was observed in the zigzag-shaped structures larger.