Polarization interaction in relation to structure of liquid metals

Abstract

Following a short review of progress in understanding structure and forces in simple liquid metals such as Na and K, and in particular the role of the conduction electrons in mediating long-range oscillatory effective ion-ion interactions, attention is focused on polarization interactions. In such bulk liquid metals, oscillatory pair potentials ø(R) of the long-range asymptotic form cos(2k ^F R)/R ³, where k _F is the Fermi wavenumber, are shown to be corrected at large R by a polarization term falling off as R ^-4. The modifications brought about when the polarization interaction takes place in a heterogeneous environment such as that in a metal surface liquid or solid are discussed. The oscillatory interaction for a pair of ions parallel to such a planar metal surface is already known to be of shorter range than in bulk liquid metals, namely, cos (2k _F R)/R ⁵. It is demonstrated here that for this same parallel configuration the polarization is also of short range, falling off as R ^-8. The case of arbitrary orientation is also mentioned.