SUPERCONDUCTING AND TRANSPORT ELECTRON-PHONON COUPLING-CONSTANTS IN YBA2CU3O7 - EFFECT OF THE INTERBAND ANISOTROPY

Using previously reported first-principle frozen-phonon LDA calculatio ns we have calculated the effective superconducting and transport elec tron-phonon coupling constants. We have taken into account the anisotr opy due to the difference between four bands crossing the Fermi level in YBa2Cu3O7, and found that because the anisotropy influence both ele ctron-phonon coupling constants, but in the opposite direction, the su perconducting constant becomes larger than the transport one. The abso lute values of the effective coupling constants is close to 2. The sup erconducting gaps for the different bands vary by nearly an order of m agnitude. We also discuss how various experiments might have been expl ained in terms of the interband anisotropy.