UNIFIED DESCRIPTION OF METALLIC AND NEUTRAL LIQUIDS AND PLASMAS

A formulation to evaluate equilibrium properties of a non-simple metallic liquid and plasma is presented in a unified fashion involving a neutral liquid as a special case; a multi-centre problem is to be solved in a coupled manner with a single-centre problem in this formulation. A liquid metal or a plasma is taken as a binary mixture of nuclei and electrons. Firstly, an inhomogeneous nucleus-electron mixture caused by fixing a nucleus at the origin is investigated by the density-functional theory for a single-centre problem to determine the internal electronic structure of an ion at the origin, which enables us to think of a liquid metal as an ion-electron mixture composed of ions with the same electronic structure as the central ion so built up at the orgin. Thus, the radial distribution functions, a self-consistent potential for electrons and the ionic charge are obtained, if the bare ion-ion interaction is given beforehand; these quantities are used to solve the following multi-centre problem. Secondly, the problem of treating a homogeneous nucleus-electron mixture is reduced to the multi-centre problem of an inhomogeneous electron gas under the external potential caused by randomly distributed nuclei. Thus, this system is shown to be regarded as a classical one-component fluid described by an effective Hamiltonian, with the same interparticle potential as the effective interionic interaction obtained in the previous single-centre problem; a bare ion-ion interaction is now created by an extension of the Gordon-Kim (GK) or tight-binding bond (TBB) model. This formulation offers a generalization of the GK and TBB methods to take account of the presence of the conduction electrons with use of self-consistent bound-state functions in a liquid. Here, a bound state is defined as a state with a negative eigenvalue or a resonant state with a long lifetime. The internal energy of a liquid metal is expressed in terms of output from the single-centre problem based on the nucleus-electron model.