  The model that explains many of the details of superconducting and magnetic
phase diagrams of YBa2Cu3O{6+/delta} and La2-xSrxCuO4 is presented. The model
is based on the assumption of rigid localization of doped charges in the close
vicinity of doped ion. This localization results in local variation of
electronic structure of the parent charge-transfer insulator that depends on
the local mutual arrangement of the doped charges. It is shown that in such
system the negative-U centers (NUCs) may form under certain conditions on the
pairs of neighboring Cu cations in CuO2 plane. We consider the mechanism of
hole generation. The calculated dependences of hole concentration in
YBa2Cu3O{6+/delta} on doping and temperature are found to be in a perfect
quantitative agreement with experimental data. In the framework of the model
the phase diagrams of YBa2Cu3O{6+/delta} is considered and the interpretation
of pseudogap and 60 K-phases in YBa2Cu3O{6+/delta} is offered. The pseudogap
has superconducting nature and arises at temperature T*>Tc/inf>Tc in small
clusters uniting a number of NUCs due to large fluctuations of NUC occupation.
(Tc/inf and Tc are the temperatures of superconducting transition for infinite
and finite clusters, accordingly). The calculated T*(/delta) and Tc(/delta)
dependences are in accordance with experiment. The range between T*(/delta) and
Tc(/delta) corresponds to the range of fluctuations where small clusters
fluctuate between superconducting and normal states owing to fluctuations of
NUC occupation. The phase diagram of La2-xSrxCuO4 is calculated. It is shown
the features of the superconducting phase diagram and the characteristics of
stripe textures of La2-xSrxCuO4 only reflect the geometrical relations existing
in a square lattice and the competition of different types of dopant ordering.
