ISOTHERMAL DENSITY DERIVATIVE OF S(K) AND THE TRIPLET CORRELATION-FUNCTION - AN EXPERIMENTAL-STUDY IN LIQUID KR

Recent accurate measurements performed on liquid Kr have been used to test some of the models proposed in the literature for the triplet correlation function 93(r, s). It turns out that neither the superposition approximation suggested by Kirkwood (J.P. Hansen and I.R. McDonald, Theory of simple liquids, Academic Press, London, 1986), nor a modification of it which partially takes into account linear density effects (H. Fredrikze, Ph.D. Thesis, Delft, 1985) are able to satisfactorily reproduce the experimental isothermal derivatives of the structure factor. Also the uniform fluid model (P.A. Egelstaff, D.I. Page and C.R.T. Heard, J. Phys. C, 4 (1971) 1453), gives a poor representation especially at lower densities. It is concluded that, in order to correctly describe triplet correlation effects, a full account of the irreducible contributions to g3(r, s) is necessary.