A DFT investigation on the mechanical and structural properties of halogen- and metal-adsorbed silicene nanosheets

Abstract

Herein, the effects of halogen and metal atomic adsorption on the mechanical and structural characteristics of silicene are studied using density functional theory (DFT) calculations. Cl, Br, Au, Ca, Ga, Li, and Na atoms are selected as the adsorption atoms. Moreover, the phonon dispersion and electron localization function are investigated to show the stability of considered nanostructures and to visualize the bonding properties, respectively. It is shown that the adsorption leads to decreasing the elastic and bulk moduli of some structures, while it increases them in some other structures. It is seen that except for Ca-adsorbed nanosheet, both the elastic and bulk moduli of all other structures decrease after adsorption. Furthermore, the isotropic behavior of all the studied nanosheets is indicated. The plastic behavior is also analyzed. It is revealed that the second critical strain of all nanosheets, except for SiBr and SiCl, decreases under uniaxial loading. However, under biaxial loading conditions, the second critical strain of Au-, Ca-, and Ga-adsorbed structures decreases, while in other structures (SiBr, SiCl, SiLi, and SiNa) the adsorption increases the yield strain.