Interlayer relaxation of W(1 1 0) studied by surface X-ray diffraction

The structure of the clean, unreconstructed W(1 1 0) surface was investigated by surface X-ray diffraction. The analysis of the integer order crystal truncation rods up to a maximum momentum transfer of four reciprocal lattice units indicates a contraction of the first interlayer distance by Δd12=−2.7(5)% relative to the bulk interlayer distance (dbulk=2.238 Å). The relaxation of the second interlayer spacing is found to be smaller than 0.3%. Within the error bars our results agree with recent low energy electron diffraction studies. However, Δd12 is lower than predicted by recent calculations (−4.1%).