Structure of liquid alkali metals as electron-ion plasmas

The application of the electron-ion plasma approach, in which the structure of a liquid metal is directly obtained from the structure of a bare ionic plasma linearly screened by a homogeneous electron gas, to the description of the structure of liquid alkali metals is examined. An analytic expression for the structure factor of a one-component plasma is obtained from an extension of the charged-hard-sphere approach of Gillan (1974) which takes into account the virial theorem, the requirement of thermodynamic consistency and the known equation of state of the one-component plasma. Experimental X-ray diffraction data for the static structure factor of liquid sodium near freezing are shown to be in very good agreement with theoretical values under certain empirical assumptions, and the predicted dependence of the structure factor on the thermodynamic state of the liquid metal is shown to be in agreement for the temperature dependence of sodium and the pressure dependence of rubidium.