Surface effects in the electronic properties of YBa2Cu3O7

The electronic structure of basal plane surfaces of the high-T, superconducting material YBa,Cu,O, has been determined using a tint-binding Hamilto~~n derived from a first-p~nciple calculation of the bulk phase. The surface local density of states has been obtained for four different surface configurations, which differ for the yttrium and oxygen content. The results show that the presence and state of the surface have a strong influence on the distribution of single particle states. The nature of the surface induced modifications is detailed and the relevance of the results to the understanding of experimental data is shortly discussed.