12-10U

The spectral density and phase diagrams have been obtained for two-sublattice Hard-core boson model in frames of random phase approximation approach. Chemical potential level in charge ordered phase (CDW) is located in the gap between the bands. In Mott insulator phase (MI) the chemical potential level is either above or below both bands while in bose-condensate (also called superfluid or SF) phase it is localized within one of the bands. The phase diagrams illustrate the transitions between these phases at various temperatures and other model parameters.