ROLE OF THE SURFACE ELECTRONIC RESPONSE FUNCTION ON TREATMENTS OF THE LIQUID-VAPOR INTERFACE OF ALKALI-METALS

We present a treatment of the surface of liquid alkali metals based on a perturbative expansion to second order in the electron-ion pseudopotential. We make a simple direct approximation for the inhomogeneous electronic response function, in contrast to previous work which approximates the effective pair interaction. It is found that the surface tension, obtained by using a nonmonotonic parametrization of the ionic profile, is in good agreement with the experimental value and improves the results of the previous approaches.