Influence of nonmagnetic impurities and defects on superconducting pairing correlation with S* - and dx2-y2-symmetry and localization of Cooper pairs condensate in high-Tc superconductors

The pairing correlation function in the Cu4 O8 cluster have been calculated by exact diagonalization. It has been shown that under hole doping there are no pairing correlations with s-symmetry and that the correlations with s*-symmetry are considerably stronger than the correlations with dx2-y2-symmetry. The influence of Anderson disorder with degree W on pairing correlations with S*-and dx2-y2-symmetry has been investigated. The enhancement of the disorder has been found to result in significantly faster weakening of the correlations in the dx2-y2-channel than in the s*-channel. Under electron doping the correlations with s- and dx2-y2-symmetry are absent and correlations with s*-symmetry are weakly dependent on W. The results obtained, along with the hypotheses for the localization of Cooper pairs condensate, provide a self-consistent picture of the influence of nonmagnetic impurities and defects on p- and n-type high-Tc superconductors