ELECTRON-PHONON INTERACTION AND ITS MANIFESTATION HIGH-TEMPERATURE SUPERCONDUCTORS

Different types of band structure approaches for a description of elec trons in systems with strong correlations are discussed. It is shown t hat all methods considered give different electron energy dispersions and Fermi surfaces. The good agreement between measured Fermi surfaces and those calculated by LDA. shows that the spatial dispersion of the correlation interaction is not so important in HTSC systems. The same conclusion can be obtained from the optical and photoemission spectre . It is shown that the most important contribution beyond a band struc ture approach is given by an energy dependence of the electron self-en ergy. The most likely interaction responsible for this energy dependen ce is the electron-phonon one. Evidences about this fact are given.