Spectroscopic examination of the Na/Si(111)-(3×1) surface structure

We have examined a recently proposed experimental model for the alkali-metal induced Si(111)-(3×1) surface structure, based on density-functional theory calculations and their comparison with experiments on the structural and electronic properties of Na/Si(111)-(3×1). This model, characterized by the alkali-metal adsorption in empty channels and the resulting honeycomblike substrate reconstruction, is energetically favored and reproduces well the experimental scanning-tunneling-microscope images, surface-state band structure, and Si 2p surface core-level spectra, which together provide a convincing theoretical demonstration that the employed model is acceptable both in energetics and in spectroscopic examination.