Atomic geometry and surface-state spectrum for Ge(111)-(2×1)

Abstract

The $\pi$-bonded chain model is studied for Ge(111)-(2×1). The minimum-energy chain geometry is found with the use of the Hellmann-Feynman forces. A buckling of the surface atoms in the chain is energetically favorable. This buckling is associated with rehybridization ($s{p}^3$ to $s{p}^2$) effects. Theoretical surface-state dispersions for this geometry are compared with recent angle-resolved photoemission experiments.