Density-functional investigation of alloyed metallic nanowires Original Research Article

Density-functional band-structure calculations for two-shell metallic nanowires from Au and from AgAu and PdAu alloys yield an increasing stability of the wires in the order [PdAu8]n < [Au9]n < [AgAu8]n. This trend coincides with the tensile stress obtained for a monatomic wire at the equilibrium geometry of the central monatomic chain. An electronic structure analysis shows that in Au9 and AgAu8 the central conductance channel is populated, in PdAu8 not. An analogous depopulation is obtained for Au9 and AgAu8 only by straining the wires in the elastic regime. These findings rationalize the lower conductivity of PdAu nanocontacts compared with AgAu contacts obtained by break junction experiments.