Condensate fraction and momentum distribution in the ground state of liquidHe4

Calculations of the condensate fraction and momentum distribution of liquid ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ are carried out using variational ground-state wave functions containing two-body (Jastrow) and three-body correlations. These wave functions give a satisfactory description of the equation of state of the liquid at T=0. The calculations are performed within the scheme of hypernetted-chain equations, using the scaling approximation for evaluating the contributions of the elementary diagrams. Results are reported at densities ρ=0.365${\sigma }^{\mathrm{-}3}$, 0.401${\sigma }^{\mathrm{-}3}$, and 0.438${\sigma }^{\mathrm{-}3}$, and compared with momentum distributions obtained from experimental data and Green’s-function Monte Carlo calculations.