  We analyze the microstructure of He-II in the framework of the method of
collective variables (CV), which was proposed by Bogolyubov and Zubarev and was
developed later by Yukhnovskii and Vakarchuk. The logarithm of the ground-state
wave function of He-II, ln(Psi_0), is calculated in the approximation of "two
sums", i.e., as a Jastrow function and first (three-particle) correction. In
the CV method equations for Psi_0 are deduced from the N-particle Schro'dinger
equation. We also take into account the connection between the structure factor
and Psi_0, which allows one to obtain Psi_0 from the structure factor of He-II,
not from a model potential of interaction between He-II atoms. It should be
emphasized that the model does not have any free parameters or functions. The
amount of one-particle (N_1) and two-particle (N_2) condensates is calculated
for the ground state of He-II: we find N_1=0.27N and N_2=0.53N in the Jastrow
approximation for Psi_0, and, taking into account the three-particle correction
to ln(Psi_0), we obtain N_1=0.06N (which agrees with the experiment) and
$N_2=0.16N. In the approximation of "two sums", we also find that the higher
s-particle condensates (s>2) are absent in He-II at T=0.
