Figure 1

(Color online) Top view (lower panels) and side view (upper panels) of the optimized structures of adsorbed ${\mathrm{H}}_2\mathrm{O}$ on Pd {100} surface: (a) $\alpha$-atop, (b) $\beta$-atop, (c) $\beta$-bridge, (d) $\gamma$-bridge, (e) $\alpha$-hollow, (f) $\beta$-hollow, and (g) $\gamma$-hollow. The plane directions for each panel were indicated in the rightmost panels. The adsorption energies as well as structural parameters for each configuration are listed in Table .Reuse & Permissions

Figure 2

(Color online) The two-dimensional (2D) contour plots of electron density difference for water adsorption on Pd {100}. (a) $\alpha$-atop, (b) $\beta$-bridge, (c) $\gamma$-bridge, (d) $\alpha$-hollow, (e) $\beta$-hollow, and (f) $\gamma$-hollow adsorption. Cross sections are shown in directions passing through the oxygen atom as indicated in Fig. 1. The plots were obtained by subtracting from the adsorption system the densities of a clean Pd stab and a ${\mathrm{H}}_2\mathrm{O}$ molecule: $\Delta n\left(\mathbf{r}\right)=n^{\text{water}∕\text{metal}}\left(\mathbf{r}\right)-n^{\text{metal}}\left(\mathbf{r}\right)-n^{\text{water}}\left(\mathbf{r}\right)$. The 2D contour maps were drawn in linear scale from $\left[\Delta n{\left(\mathbf{r}\right)}_{\min }\right]$ to $\left[\Delta n{\left(\mathbf{r}\right)}_{\max }\right]$, represented by the color gradient. Negative $\Delta n\left(\mathbf{r}\right)$ indicates loss of electron density upon binding, while a positive one corresponds to electron density accumulation. The values of $\Delta n{\left(\mathbf{r}\right)}_{\min }$ and $\Delta n{\left(\mathbf{r}\right)}_{\max }$ are also shown on the right side of each map; the white balls mark the position of Pd atoms.Reuse & Permissions

Figure 3

(Color online) Density of states of (a) $\alpha$-atop and (b) $\beta$-atop adsorptions. The 3D isosurface value of the electron density difference (inset) is set at $\pm 0.005e∕{\mathrm{A}}^3$.Reuse & Permissions

Figure 4

(Color online) Density of states of the (a) $\beta$-bridge and (b) $\gamma$-bridge adsorptions. The 3D isosurface value of the electron density difference (inset) is set at 0.005 and $\pm 0.004e∕{\mathrm{A}}^3$, respectively.Reuse & Permissions

Figure 5

(Color online) Density of states of the (a) $\alpha$-hollow and (b) $\beta$-hollow adsorptions. The 3D isosurface value of the electron density difference (inset) is set at $\pm 0.004$, $\pm 0.004$, and $\pm 0.002e∕{\mathrm{A}}^3$, respectively.Reuse & Permissions