Calculation of interband optical conductivity of Tl2CaBa2Cu2O8 and Tl2Ca2Ba2Cu3O/sub 10/ superconductors

The interband optical conductivities of Tl2CaBa2Cu2O8 and Tl2Ca2Ba2Cu3O/sub 10/ superconductors are calculated by using a first-principles method. The results for the two compounds are quite similar, both showing strong anisotropy behavior and a strong momentum matrix effect. The complex dielectric function, the electron energy-loss function, and the reflectivity spectrum are then derived. The values of the static dielectric constant ε0 and the plasmon frequency ω/sub p/ are also obtained. These optical properties are discussed together with similar results for the YBa2Cu3O7 and Bi2CaSr2Cu2O8 superconductors. Implications of these results on the possible mechanism in these compounds are discussed