Truncation-induced multilayer relaxation of the A1(110) surface

Results from a low-energy electron diffraction (LEED) analysis of the A1(110) surface are presented and discussed. The results indicate that a multilayer relaxation exists in the A1(110) surface region such that the spacing between layers 1 and 2 has a relative change $\Delta d_{12}$ of -8.5% from the bulk value, while $\Delta d_{23}=+5.5\%$, $\Delta d_{34}=+2.2\%$, and $\Delta d_{45}=+1.6\%$. When these results are compared with those from an independent LEED analysis, excellent agreement is found between results for $\Delta d_{12}$ and $\Delta d_{23}$. However, a disagreement is found to exist between the results of the two analyses for $\Delta d_{34}$. When this disagreement is considered in relationship to predictions of a recent theory for the multilayer relaxation of metallic surfaces, the importance of future work to resolve this $\Delta d_{34}$ discrepancy is apparent.