Ge(111)2×1:π-Bonded Chain Model or Not?

Abstract
Contrarily to other recent photoemission experiments the authors find that the danglingbond surface state of Ge(111)2×1 has a band dispersion very different from the one predicted by theoretical calculations based on an optimized chain model. The applicability of the π-bonded chain model to Ge(111)2×1 is questioned.