Binding distance ofc−(2×2)O on Ni(001)

The binding distance of $c(2\mathrm{}\times 2)$ O on Ni(001) was studied in detail by low-energy electron diffraction. We calculated intensity-voltage curves at normal and off-normal incidences for O-Ni interlayer spacings 1.3 Å down to 0.0 Å, using the combined-space method. Comparisons with experimental data show that there is no improved agreement for any of the spacings over the original value of $d_{\perp }=0.9\mathrm{}$ Å. However, the values of $d_{\perp }=0.9\mathrm{}$ and $d_{\perp }\le 0.1$ Å show roughly the same fit. A normalized $R$ factor also gives double minima of approximately the same depth at these two spacings.