Properties of Mg2Si (100) surfaces: A first-principles study

• Mg- and Si-terminated Mg2Si (100) surfaces were studied with a DFT–GGA method.
• Effects of relaxation are mainly localized within the top three atomic layers for both terminations.
• Mg-terminated surfaces are more stable than Si-terminated surfaces.
• Mg-terminated surfaces show metallic feature, while Si-terminated surfaces have semiconducting property.

The Mg2Si (100) surfaces were studied using first-principles method based on the density functional theory (DFT) to explore the surface properties. It is demonstrated that eleven-layers for Mg-terminated surfaces and nine-layers for Si-terminated surfaces all converged well. The surface relaxation indicates that the effects of relaxation are mainly localized within the top three atomic layers for both terminations. The calculation results of surface energies show that Mg-terminated surfaces are more stable than Si-terminated surfaces. The electronic structure not only reveals the metallic feature for the Mg-terminated surfaces and semiconducting property for the Si-terminated surfaces, but also indicates the existence of covalent bonding in Mg2Si (100) surfaces.