The structural and electronic properties of the $\mathrm{S}\mathrm{n}/\mathrm{S}\mathrm{i}\left(111\right)\mathrm{}\sqrt{3}\times \sqrt{3}$ surface are determined by means of all-electron local density full-potential augmented plane wave thin film calculations. We find strong similarities with the more extensively studied isolectronic systems (Sn/Ge and Pb/Ge) as far as the relaxed structure and the electronic properties are concerned. In analogy with these systems, we find, within the local density approximation (LDA), two surface states weakly dispersed in the Brillouin zone which are responsible for the hexagonal patterns observed in scanning tunneling microscopy (STM) experiments. When our calculated results, including STM images, are compared with available structural data and STM images, we find that the LDA predictions well reproduce the electron distribution at the surface and the structural properties, leading to a complete description of this system at room temperature.

• Received 21 December 1999

DOI:https://doi.org/10.1103/PhysRevB.62.1556