The atomic arrangement on a (11•0) surface was determined by means of quantitative low-energy electron diffraction intensity analyses. The surface arrangement was found to be different to the bulk structure in 2 respects. One was that the spacing between the first and second layers, both of which had 2 inequivalent atoms in the unit mesh, was contracted by 2.7% (0.005nm). The other was that 2 inequivalent atoms in the first layer translated parallel to the surface, by equal and opposite amounts, to 0.01nm. Thus, the change in registration of the composite surface layer preserved both the size and the symmetry of the unit mesh of parallel bulk layers. This type of surface rearrangement was a relaxation, and was very similar to the relaxation found on the (11•0) Tb surface, but was quite different to published reconstructions for the (11•0) surfaces of rare-earth metals such as Y, Ho and Er.

J.Quinn, C.P.Wang, F.Jona, P.M.Marcus: Journal of Physics - Condensed Matter, 1993, 5[5], 541-50