Hydrogen dissociation over Au nanowires and the fractional conductance quantum.

The dissociation of H2 molecules over stretched Au nanowires and its effect on the conductance are analyzed using a combination of density functional theory (DFT) total energy calculations and nonequilibrium Keldysh-Green function methods. Our DFT simulations reproduce the characteristic formation of Au monatomic chains with a conductance close to G0=2e2/h. These stretched Au nanowires are shown to be better catalysts for dissociation than Au surfaces. This is confirmed by the nanowire conductance evidence: while insensitive to molecular hydrogen, atomic hydrogen induces the appearance of fractional conductances (G approximately 0.5G0) as observed experimentally.