Figure 1

(a) Total energy variation versus elongation distance of suspended Au NWs for the molecular (i) and dissociative (ii) oxygen incorporation modes. Selected relaxed atomic configurations are displayed, with the smaller spheres (blue) denoting the oxygen atoms. Bottom panel: the elongation force for mode (i); each of the spikes corresponds to a tip atom joining the NW. The definitions of $L_0$ (the length of the contact region connecting the two leads) and $L_{\mathrm{gap}}$ (the NW length) are included in configuration a of (a)(ii). (b) Excess electronic charge distribution on the oxygen molecule embedded in the NW, calculated for state D in (a)(i) as the difference between the charge density of the combined Au $\mathrm{NW}/{\mathrm{O}}_2$ system and the densities of the individual components (i.e., Au NW and ${\mathrm{O}}_2$ molecule). Excess charge, located mostly on the oxygens, is denoted by shadowed (blue) surfaces. Gold atoms (yellow) and oxygens (red) are located as in configuration D shown in (a).Reuse & Permissions

Figure 2

(a) Variation of the conductance (in units of $G_0=2e^2/h$) of a suspended Au NW with incorporated molecular oxygen, plotted versus the wire elongation. The letters on the curve correspond to the configurations shown in Fig. 1a. The results for mode (ii) NW are shown in the inset. (b) Isosurfaces [denoted by shadowed regions (green)] of the density of electrons with energy near $E_F$, $n(\mathbf{r};E_F)$, for states C (left) and E (right) of mode (i) oxygenated Au [see also Fig. 1a(i)]. In state C (E) $L_{\mathrm{gap}}=10.01\AA$ (13.71 Å), the average distance between Au atoms is 2.59 Å (2.72 Å), $d_{\mathrm{O}(1)\mathrm{\text{−}}\mathrm{O}(2)}=1.36\AA$ (1.38 Å), $d_{\mathrm{Au}\mathrm{\text{−}}\mathrm{O}}=2.10\AA$ (2.24 Å) and 2.11 Å (2.05 Å). Note the pronounced structural asymmetry of the 5 Au atom configurations starting from D [Fig. 1a(i)]. In the above, $n(\mathbf{r};E_F)=\sum _{j,s}[1-2|f(j,s)-0.5|]|\Phi j,s(\mathbf{r}){|}^2$, where $\Phi j,s(\mathbf{r})$ and $f(j,s)$ are, respectively, the Kohn-Sham orbital and the Fermi-Dirac distribution function for energy level $j$ with spin $s=\pm \frac{1}{2}$, and a Fermi temperature $k_B{T}_F=0.014\mathrm{eV}$. Larger spheres (yellow) depict gold atoms, smaller ones (red) correspond to oxygen atoms.Reuse & Permissions

Figure 3

Projected densities of states (PDOS, in arbitrary units) on one of the oxygen atoms for (a) mode (i) [corresponding to D in Fig. 1a] and (b) mode (ii) [corresponding to configuration a in Fig. 1a, inset] of the oxygenated Au NWs. (c) PDOS projected on the central Au atom for the mode (ii) NW. The Fermi level is at zero. Solid (blue) lines denote $p$ states, dotted (red) lines denote $d$ states, and dashed (black) lines denote $s$ states.Reuse & Permissions

Figure 4

Magnetic moments per atom (in Bohr magneton, filled squares) for the different atomic regions (numbered as shown at the upper left corner, with the oxygen atoms denoted as 6 and 8) for configuration (a) [see Fig. 1a(ii)] of an Au NW with incorporated atomic oxygen [mode (ii)]. Inset: Total magnetic moments as a function of elongation distance, starting at $\Delta L=0$ from configuration (a); see Fig. 1a(ii). Up triangles, down triangles, and circles denote the $d$, $p$, and $s$ contributions, respectively.Reuse & Permissions