D-wave overlapping band model for cuprate superconductors

Within the BCS framework a multiband model with d-wave symmetry is considered. Generalized Fermi surface topologies via band overlapping are introduced. The band overlap scale is of the order of the Debye energy. The order parameters and the pairing have d-wave symmetry. Experimental values reported for the critical temperatures $T_c(x)$ and the order parameters, $\Delta_0(x)$, in terms of dopping $x$ are used. Numerical results for the coupling and the band overlapping parameters in terms of the doping are obtained for the cuprate superconductor $La_{2-x}Sr_xCuO_4$.