Nonperturbative ab initio approach for calculating the electrical conductivity of a liquid metal

We propose a nonperturbative ab initio approach to calculate the electrical conductivity of a liquid metal. Our approach is based on the Kubo formula and the theory of electron-phonon coupling (EPC) and, unlike the conventional empirical approach based on the Kubo-Greenwood formula, fully takes into account the effect of coupling between electrons and moving ions. We show that the electrical conductivity at high temperature is determined by an EPC parameter lambda(tr), which can be inferred, nonperturbatively, from the correlation of electron scattering matrices induced by ions. The latter can be evaluated in a molecular dynamics simulation. Based on the density-functional theory and pseudopotential methods, we implement the approach in an ab initio manner. We apply it to liquid sodium and obtain results in good agreement with experiments. This approach is efficient and based on a rigorous theory suitable for applying to general metallic liquid systems.