Topologically disordered Hubbard models and the electronic structure of expanded Cs: A numerical study

We present a numerical study of the electronic properties of simple models of expanded alkali metals. An Anderson-Hubbard model incorporating on-site electron-electron repulsion and liquid-like disorder is solved within the unrestricted Hartree-Fock approximation We focus on the proper determination of the localization properties deciding the metallic or nonmetallic character of the model and on the computation of the electrical conductivity within the random phase model. With a realistic set of parameters we obtain good quantitative agreement with experiments on expanded Cs for i) the density at which the metal-nonmetal transition occurs and ii) the electrical conductivity throughout the entire density interval accessible by experiments. The transport properties thus computed give additional support to recent claims that the description of liquid expanded metals requires the incorporation of both disorder and interaction effects.