The Change of the Electron Clouds of Ions in Cuprate Superconductor CaCuO2: A First-Principles Investigation of the Electron-Pairing

Abstract: " P. W. Anderson raised an important question in 2007: Is There Glue in Cuprate Superconductors? The author believes that the change of the electron clouds of ions is the glue in cuprate superconductors. The change of the electron clouds of the ions in the parent structure of the layered high-temperature superconductors CaCuO2 has been studied by the first-principles calculations. The electron clouds of Cu2+ and O2- ions change obviously under electric fields. It is also found, for the first time, the characteristic frequencies of the change of the electron clouds are 250 meV, 360 meV, and 100 meV, respectively, for the modes observed. The frequencies are low and close to that of lattice vibrations, indicating the change of the electron cloud of ions can be the electron-pairing medium in cuprate superconductors.