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(2e(2)/h) = 2g(0), and it drops sharply to 1g(0) during the transformation to a single chain, exhibiting subsequently a similar to 1g(0) plateau extending over an elongation well above typical Au-Au distances.