Atomic and electronic structure of the $\sqrt{3}$$\times$$\sqrt{3}$ silicene phase on Ag(111): density-functional calculations

Abstract

Density-functional theory calculations are used to verify the atomic structure of the $\sqrt{3}$$\times$$\sqrt{3}$ silicene phase grown on the Ag(111) surface. Recent experimental studies strongly suggested that the previous double-layer silicene model should be replaced with a Ag-mixed double-layer model resembling the top layers of the Ag/Si(111)-($\sqrt{3}$$\times$$\sqrt{3}$) surface. In our calculations, the Ag-mixed double-layer model is indeed energetically favored over the double-layer silicene model and well reproduces the reported scanning-tunneling microscopy and spectroscopy data. Especially, the structural origin of the experimental band structure is clarified as the top Ag-Si mixed layer, unlike the experimental interpretations as either a silicene layer or the Ag(111) substrate.