  Hole-doped cuprates demonstrate partially coexisting pseudogap, charge
density wave (CDW) and superconducting phases. Recently their common nature was
supposed due to similar doping dependence of their critical temperatures. In
the CDW phase, a large frozen deformation of strongly ionic lattice is
observed. Like for a single carrier in a highly polarizable lattice, for
multiple carriers in it the choice between delocalized states of all the
carriers and autolocalized states of some part of them is determined by minimum
of free energy of interacting carrier and phonon fields. Applying variational
approach, we calculate free energy of a two-liquid system of carriers with
cuprates-like dispersion comprising liquid of autolocalized carriers (large
polarons and bipolarons) and Fermi liquid of delocalized carriers. Comparing it
with the free energy of pure Fermi liquid and calculating (with standard
methods of Bose-liquid theory) a temperature of superfluid transition in the
large-bipolaron liquid we identify areas with presence of pseudogap (caused by
impact of (bi)polaron potential on delocalized quasiparticles), CDW and
superconductivity in a phase diagram. They are in the same places as in
hole-doped cuprates, and similarly to cuprates the shape of the calculated
phase diagram is stable with respect to wide-range change of the system
characteristics. Like in cuprates, the calculated temperature of the
superconducting transition increases with the number of conducting planes in
the unit cell, the calculated superfluid density decreases with doping at
overdoping, and the bipolaron density (together with bipolaronic plasmon
energy) saturates at optimal doping. The results obtained allow us to discuss
ways of increasing the temperature of the superfluid transition in
large-bipolaron liquid and open a possibility of studying the current-carrying
state and properties of bipolaron condensate.
