Dynamic properties of liquid metals

Abstract

The static and dynamic properties of three liquid alkali metals were studied using molecular dynamics: lithium (at 470 K), rubidium (over a temperature range from 350 to 1873 K) and cesium (just above the melting point, at 308 K). The interatomic potential is based for Li on an OPW pseudopotential and for Rb and Cs on an empty-core pseudopotential. From the raw computer data, both single-particle and collective dynamic correlation functions were extracted. Interpretation of these correlation functions in terms of hydrodynamic, memory-function and (simple) mode-coupling models allows one to derive both thermodynamic and elastic properties. The dynamic structure factors have been compared for all three metals with recent neutron-scattering data. It is found that — except for the higher temperature states of Rb (i.e., at the onset of the metal-non-metal transition) — agreement between theory and experiment is good. Concerning elastic and thermodynamic properties, differences of 10–15% with respect to the experimental data are encountered.