Semiconducting chains of gold and silver

Abstract

The authors introduce a geometry for ultrathin Au and Ag wires that ab initio calculations indicate to be more stable than previously considered planar geometries for these systems by about 0.1eV per atom. This structure is insulating for both metals and for related Ag0.5Au0.5 alloys with gaps of 1.3eV for Au, 0.8eV for Ag, and varying between 0.1 and 1.9eV for the alloys. The insulating nature of the geometry is not a result of Peierls instabilities and is analyzed in terms of an interplay between geometric and electronic structure effects.