A DFT study on the mechanical properties of hydrogenated and fluorinated germanene sheets

Abstract

The density functional theory (DFT) was used to investigate the mechanical properties of the pristine, hydrogenated, and fluorinated germanene sheets, including Young's and bulk moduli , and plastic properties . Young's and bulk moduli were calculated through the second derivation of the total energy versus strain. The electronic properties, namely the planar electron difference density and partial DOS were considered to evaluate the bonding characteristics of the structures. The results show that the adsorption decreases the electron accumulation between Ge atoms, which leads to weaker covalent bonds and reduced Young's and bulk moduli. Furthermore, it is observed that the yield strain of fully fluorinated germanene remains unchanged under uniaxial loading in comparison with the pristine structure. However, the yield strain of the hydrogenated germanene is increased under biaxial loadings. Our results show that germanene has a good mechanical tenability using surface functionalization . • DFT is used to study the bonding characteristics and mechanical properties of pure and adsorbed germanene nanostructures. • Hydrogen and Fluorine atoms are used for this purpose. • Adsorption leads to decreasing the elastic and bulk moduli of germanene. • The yield strain of adsorbed structures decreases except for FF-Ge under uniaxial and FH-Ge under biaxial loading. • Electron difference density shows weaker bonds in adsorbed structures compared to the pristine one.