EFFECTIVE PAIR POTENTIALS DESCRIBING THE MEASURED STRUCTURE FACTOR OF EXPANDED CESIUM NEAR THE CRITICAL-POINT

Some theoretical and computational works on expanded caesium near the critical point have been reported after Winter and Hensel's neutron diffraction experiments. Here we present effective pair potentials almost reproducing the observed structure data (T = 1923 K, rho = 0.59 g/cm3). In order to obtain such effective pair potentials we use four types of reference potentials: a hard-sphere potential, a hard-sphere Yukawa potential, a Lennard-Jones potential and a pair potential derived from the pseudopotential theory. The final effective pair potentials reconstructed in this work almost equally reproduce the observed structure factor of expanded caesium at 1923 K within the accuracy of the Percus-Yevick approximation. A molecular dynamics calculation is also presented in. comparison with these results.