  Based on the collective variables representation with the Hermitian form of
Bogoliubov-Zubarev Hamiltonian the self-consistent oscillator model of a ground
state and excited states of Bose liquid has been proposed. The new method of
calculation of anharmonic terms in this Hamiltonian and its interpretation have
been presented. The dispersion equation for a collective excitation in a
superfluid $^{4}$He has been obtained in self-consistent way, where real and
virtual processes of decay of a collective excitation were considered. The end
point, determined by a threshold of collective excitation's decay on two
rotons, of the dispersion curve has been obtained and it was shown that the
dispersion curve strongly depends on property of its stability. An approach
with a structure factor has been realized without using of any adaption
parameters. Based on the oscillator model the new method of self-consistent
calculation of a ground state energy and density of Bose condensate has been
proposed. The model of suppression of Bose condensate has been presented.
