Generalized viscosity, pair potential, and memory functions from S(q,ω) measurements for liquid metals

The aim of the present work is to perform an in-depth analysis of neutron scattering data on liquid metals and to extend previous types of comparisons between experimental scattering functions and various model theories. The kinematic viscosity ν(q) for some liquid metals—liquid lead at 623 and 1173 K, liquid bismuth at 578 K, and liquid rubidium at 315 K—is derived, based on the dynamical scattering functions S(q,ω), and compared to molecular dynamics data for hard spheres. The general behavior of the ν(q) curve is traced. With use of an analytical form of pair potential with several free parameters, a form of V(r) for liquid lead at 623 K is derived. Finally, the short-time interaction part of the experimental memory function ${\Phi }_l$(q,t) for the longitudinal current correlation function is directly compared to the corresponding result calculated from kinetic theory in the mode-coupling version. This comparison is based upon the derived form of the interatomic potential for Pb at 623 K and upon other known potential data for Rb at 315 K.