Liquid atomic motions from line width studies of scattering functions s(k,ω) and ss(k,ω)

Abstract

Abstract In recent years accurate experimental values of the FWHM (full width at half maximum) of the scattering functions S(k,ω) were published. Similarly molecular dynamics studies were produced for the corresponding widths for self motion for liquid argon and rubidium. Combining knowledge from these two fields sheds some new light on the connections between self motion and collective motions in the liquids. In the present work four fluids are considered, namely argon, rubidium, lead and bismuth. It is argued that the study of these line widths gives considerable insight into the nature of the self diffusion process even if the wave vectors involved are such that k > ko, where kO, is the wave vector value at which the liquid structure factor has its main maximum. Effects of self motion dominate in this region. When k < kO the collective effects in S(k, ω) dominate completely and the importance of self motion disappears as k → 0.