ROLE OF THE SURFACE ELECTRONIC RESPONSE FUNCTION ON TREATMENTS OF THELIQUID-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 pseudopo tential. We make a simple direct approximation for the inhomogeneous e lectronic response function, in contrast to previous work which approx imates the effective pair interaction. It is found that the surface te nsion, obtained by using a nonmonotonic parametrization of the ionic p rofile, is in good agreement with the experimental value and improves the results of the previous approaches.