  We suggest a model for electronic structure of cuprate superconductors that
makes it possible to describe evolution of this structure with the doping and
provides a new explanation for a number of typical features of cuprates,
including the pseudogap and the Fermi arcs. According to this model, the unique
electronic structure of cuprates is favorable for the formation of two-atomic
negative-U centers (NUCs) and realization of a peculiar mechanism of the
electron-electron interaction.
