Superconductivity in YBa2Cu3O7:: A two-dimensional phenomenon?

Starting from an ab initio calculation of the electronic structure of YBa2Cu3O7, we have analyzed in detail the formulations of some of the 2D theories of the phenomenon of superconductivity. We assume that if Cooper pairs are formed by electronic states belonging to the CuO2 plane, these states should show as the majority contribution in a 3D formulation as well. From our analysis we conclude that 2D theories could neglect important information and as a consequence, some of the experimental results remain unexplained. The 3D formulation has been analyzed before in a restricted way with promissory results. Our preliminary explanation of some of the newest experimental data is very stimulating.