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 densi ty 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 s urface 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 alr eady favoured in bulk Gd. Our results indicate that LSDA leads to the wrong magnetic ground state for gadolinium.