Nanowire Gold Chains:  Formation Mechanisms and Conductance

Structural transformations, electronic spectra, and ballistic transport in pulled gold nanowires are investigated with ab initio simulations, and correlated with recent measurements. Strain-induced yield of an initial double-strand wire results first in formation of a bent chain which transforms upon further elongation to a linear atomic chain exhibiting dimerized atomic configurations. These structures are stabilized by directional local bonding with spd hybridization. The conductance of the initial double-stranded contact is close to 2(2 e 2 / h ) ≡ 2 g 0, and it drops sharply to 1 g 0 during the transformation to a single chain, exhibiting subsequently a ∼1 g 0 plateau extending over an elongation well above typical Au−Au distances.