  The existing theory about the cuprate superconductor bases on band theory,
almost all neglects the position difference of Cu-O ions on CuO2 plane, and
assumes that the charge on ions are averagely distributed. Considering that the
nature of conduction is the moving of electrons, carrier means electron in this
article. The charge opposite the carriers distributes on fixed ions, and the
position difference of Cu-O ions slightly violates average electricity
distribution, so the concept of hole is not suitable. It is proved that, near
the optimal doping level, since the density of ions is relatively low, the
violations can be treated as a perturbation, and the ion lattice can be seen as
a combination of regular lattice and dipole lattice. Considering about that the
character of cuprate superconductor is mainly dominated by the dipole lattice,
the pairing mechanism, the d-wave symmetry, and the linear temperature
dependence of normal state resistivity is tersely interpreted.

Superconductivity