Electron Redistribution at Monovacancy in Graphene

Abstract

Abstract Body: Vacancy defects are unavoidable in 2D materials due to the challenges involved in fabricating defect-free lattice from experimental methods. While defects are known to degrade the mechanical properties of a lattice, they offer unique opportunities to tailor the electronic and thermal properties by controlling the mean free path of electrons and phonons. It is therefore important to develop a fundamental understanding of the role of defects in modulating the local electronic character of a lattice. Nevertheless, the understanding of defect-induced alteration of electronic properties (the electronic states for example) remains less understood, particularly under finite deformation. Although researchers have investigated the mechanical and electronic properties of pristine graphene under stress, there is little research on the chirality effects on electron distribution at defective sites in 2D materials under applied stress. In this work, we use the density functional theory simulations and the Mulliken charge population analysis to investigate the electronic behavior of an isolated defect in graphene under the uniaxial loading condition for five different chiralities of the lattice. We analyze how chirality and intensity of loading affect the mechanical properties, bond length and bond angle change, charge distributions, the density of states, and the partial density of states surrounding the vacancy. Our results show that there is a uniform pattern for bond length redistribution as well as electron redistribution at all orientation angles and that such bond and electron redistributions are directly correlated. During all simulations, we observe a bond reconstruction at the defective site at higher deformation. In terms of the orientation angle, we demonstrate that increased orientation angle yields changes in the strength, toughness, stiffness, bond distributions, and electronics surrounding a mono vacancy. We find that differing orientation angles result in different failure processes and speeds. Additionally, the redistribution at the defective site is chirality-dependent, and there is a significant localization of electronic states at the defective site. The pattern of density of states is deformation-dependent. This talk will present a comprehensive view on the specific effects of electron redistribution on mechanical and electronic characteristics of the defective lattice.