STRUCTURE PROPERTIES OF THE HE-3-HE-4 MIXTURE AT T=0-K

The spatial structure properties of He-3-He-4 mixtures at T = 0 K are investigated using the hypernetted-chain formalism. The variational wa ve function used to describe the ground-state of the mixture is a simp le generalization of the trial wave functions for pure phases and cont ains two- and three-body correlations. The elementary diagrams are tak en into account by means of an extension of the scaling approximation to the mixtures. The two-body distribution (g(alpha, beta) (r)) and th e structure functions (S(alpha, beta) (k)) together with the different spin-spin distribution functions of the He-3 component in the mixture are analyzed for several concentrations of He-3. Two sum-rules, for t he direct and the exchange part of the g(3, 3) (r), are used to ascert ain the importance of the full treatment of the Fermi statistics in th e calculation. The statistical correlations are found responsible for the main differences between the several components of the distributio n function. Due to its low concentration, He-3 behaves as a quasi-free Fermi gas, as far as the statistical correlations are concerned, alth ough it is strongly correlated with the He-4 atoms through the interat omic potential.