Ab initio calculation of the structure, the electronic states and the phonon dispersion of the Si(111)-(2x1) surface

We have investigated the structural, electronic, and dynamical properties of the Si(111)-(2 x 1) surface within the density functional theory. We have found two equilibrium configurations consistent with the pi-bonded chain model. Bring almost equal in total energy they show a reverse tilt angle of the surface chains. The calculated electronic structure for both the positive and the negative buckling is in good agreement with photoemission data. An ab initio linear-response formalism has been used to determine the surface phonon dispersion curve for both configurations along the <(Gamma J)over bar> direction in the surface Brillouin zone.