LSDA CALCULATIONS FOR MAGNETIC-STRUCTURES OF GD BULK AND THE GD(0001) SURFACE

We perform self-consistent linear-muffin-tin-orbital calculations with the atomic-sphere approximation (LMTO-ASA) within density functional theory, for Gd bulk and its (0001) surface, using the local spin density approximation (LSDA). We treat the 4f electrons as intinerant band-states which has been found important for the realistic description of bulk Gd. From our calculation the antiferromagnetic coupling of the surface with the bulk magnetic moment emerges energetically favourable to a ferromagnetic one. Analysing these results further, we find - in contradiction to experiment - that this antiferromagnetic order is already favoured in bulk Gd. Our results indicate that LSDA leads to the wrong magnetic ground state for gadolinium.