A Note on the Electronic States in Liquid Metals

The energy spectrum of valence electrons in liquid metals is investigated with the nearly free-electron approximation (Ziman's picture). The spectrum in monovalent (alkali) liquid metals is essentially the free one with small increase of the density of states on the Fermi surface. In the case of polyvalent metals, the spectrum is distorted by the electron-ion interaction reflecting complicated ionic distribution. The density of states near the Fermi surface increases by a factor of about two compared to that of free electrons. The energy spectrum seems to characterize a liquid metal from others to some extent as it does a solid. Qualitative feature of several electronic properties is discussed in relation to the ionic density correlation, i.e. the structure factor of neutron diffraction of a liquid metal. Several ex perimental facts for the electronic structure in liquid metals, e.g. the soft X-ray emission spectrum from liquid aluminium, which are thought to be incompatible with Ziman's picture, are explained reasonq_bly from the viewpoint of nearly-free-electron approximation. The dynamical effect of the electron-ion interaction is investigated in reference to Ziman's plasma term scattering. The effect is shown to cause a mass shift for thermal properties of electrons and in the case of liquid sodium the mass shift is expected to amount to the same order as in the solid.