Parallel and perpendicular multilayer relaxation of Fe{310}

We report the results of a low-energy electron-diffraction analysis of the atomic structure of the {310} surface of body-centered-cubic iron. Damped relaxations from bulklike structure are found in the directions both parallel and perpendicular to the surface and extending four layers deep into the lattice. The surface structure is as follows: first interlayer spacing d₁₂=0.76±0.03 {} (bulk value is 0.906 {}), second interlayer spacing d₂₃=1.02±0.03 {}, third interlayer spacing d₃₄=0.87±0.04 {}, change of first-to-second layer registry shift Δa₁₂=0.13±0.05 {}, and change of second-to-third layer registry shift Δa₂₃=0.03±0.05 {}. Both changes of registry shifts are in the same direction, along a $〈310〉$ axis, and cause a decrease in the difference between nearest- and next-nearest-neighbor distances between atoms in adjacent layers.