TIGHT-BINDING MODEL FOR ELECTRONIC-STRUCTURE AND ELECTRON PHONON COUPLING IN HIGH-TC SUPERCONDUCTORS (LA2-XMXCUO4)

We present a tight-binding type electronic theory for the electronic structure and electron-phonon coupling in La//2CuO//4-type compounds. We obtain simple formulas for the electron-phonon coupling which display the dominant role of breathing-mode type phonons for lattice instabilities and phonon mediated superconductivity. We estimate N(O), the strength of the electron-phonon coupling, the transition temperature T//c resulting from electron-phonon coupling and discuss the anisotropy of the superconducting-energy gap due to phonon pairing, and phonon softening resulting from electron-phonon coupling.