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

Abstract

The $\ensuremath{\pi}$-bonded chain model is studied for Ge(111)-(2\ifmmode\times\else\texttimes\fi{}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.