Dynamical Correlations in Liquid Sodium

The theory developed by Glass and Rice is used to study the atomic motions in liquid sodium in terms of the velocity autocorrelation function, power spectrum, and mean square displacement at 373 K. The interatomic pair potential for liquid sodium at the melting temperature is obtained by using Ashcroft's pseudopotential theory with the dielectric function of Vashishta and Singwi. Results of these calculations are compared with the results obtained by Miranda and Tora from molecular dynamics at 373 K. These results of dynamical variables obtained by the theory of Glass and Rice show a good agreement with the molecular dynamics results for liquid sodium. Besides, calculations are also done for the coherent behaviour of liquid sodium in terms of the dynamical structure factor S ( k , ω). Quasi dispersion curves derived from the peak positions of the longitudinal current‐current correlation function ω 2 S ( k , ω)/ω −2 against k , are in good agreement with experimental phonon dispersion results of Cocking for liquid sodium.