Static structure of dense krypton and interatomic interaction

The static structure factor S(k) of liquid krypton has been measured by neutron diffraction at temperatures T=130, 169 and 199 K and at several densities. The extended k range of the measurements, 3.6-160 nm -1 , and the high accuracy of the data allow an unambiguous computation of the radial distribution function g(r) and of the direct correlation function c(r). All three functions, S(k), g(r) and c(r), are in remarkably good agreement with the theoretical result when the Aziz pair interaction plus the triple-dipole three-body interaction are used in a triplet MHNC equation. The authors obtain definite evidence that the Lennard-Jones pair potential is not a good representation of the interatomic forces. The small remaining deviation between theory and experiment indicates the presence of some additional many-body force which is repulsive at short distance and attractive at intermediate distance.