Solution of real-axis Eliashberg equations with different pair symmetries and tunneling density of states

The real-axis direct solution of the Eliashberg equations for the retarded electron-boson interaction in the half-filling case and in the presence of impurities is obtained for six different symmetries of the order parameter: s, s + id, s + d, d, anisotropic-s and extended-s. The spectral function i s assumed to contain an isotropic part alpha (2)(is) (Omega) and an anisotr opic one alpha F-2(an)(Omega) such that alpha F-2(is)(Omega) = g (.) alpha F-2(an)(Omega), where g is a constant, and the Coulomb, pseudopotential mu* is set to zero for simplicity. The density of states is calculated for eac h symmetry;ri: T = 2, 4, 40 and 80 K. The resulting curves are compared to those obtained by analytical continuation of the imaginary-axis solution of the Eliashberg equations and to the experimental tunneling curves of optim ally-doped Bi 2212 crystals.