Estudo estrutural e eletrônico de grafinos em diferentes configurações via simulações atomísticas

Abstract

The study based on the characterization and application of nanomaterials in major areas of human knowledge is growing and developing exponentially over time. Recently, research focusing on two-dimensional nanomaterials has received significant attention

in the scientific and technological communities, as the low spatial requirement of two- dimensional nanostructures allows for increased efficiency of technological devices without

the need to increase their volume. In particular, it is worth highlighting graphene, a crystal lattice composed entirely of carbon with sp2 hybridization, which possesses remarkable mechanical and electronic qualities, such as a high Young’s modulus of around 1 TPa and exceptional electronic mobility at room temperature [1]. In light of this, this project aims to study a two-dimensional nanomaterial, a carbon allotrope similar to graphene, known as graphyne. This structure is formed by benzene rings connected by carbon chains, featuring both sp2 and sp hybridizations in its composition. Another important aspect of its geometry to be discussed is its nomenclature, denoted as graphyne-n, where n indicates the number of triple bonds in the carbon chains connecting the benzene rings. This work aims to characterize the structural and electronic properties of different conformations of graphyne-derived structures, such as G(1-5) and bilayer graphyne structures, through atomistic simulations using both semi-empirical methods (PM3, PM6) and DFT-based methods (DFTB). Another goal of this work is to develop and identify the stacking configuration, similar to graphite, of the crystal lattices derived from G(1-5). Finally, the quantities calculated in this work include, in the molecular domain, bond lengths, formation energy, and molecular GAP of all molecular structures studied. In the periodic domain, the quantities obtained are the minimum number of k-points, cohesive energy, Band Structure, and Young’s modulus for all crystal lattices studied in this work.