First-principles molecular dynamics of liquid alkali metals based on the quantal hyper-netted chain theory

Abstract

The density-functional theory proves that an ion-electron mixture can be treated as a one-component liquid interacting only via a {\it pairwise} interaction in the evaluation of the ion-ion radial distribution function (RDF), and provides a set of integral equations: one is an integral equation for the ion-ion RDF and another for an effective ion-ion interaction, which depends on the ion-ion RDF. After some approximations are introduced to the integral equation (QHNC) for the effective potential, the MD simulation and the procedure to determine the effective interaction from the QHNC equation are performed iteratively to be self-consistent (the QHNC-MD method). This method provides a first-principles calculation of structures of simple liquid metal: the ion-ion and electron-ion RDF's, the charge distributions of an ion and a pseudoatom, the effective interaction and the ion-ion bridge function are evaluated from the atomic number as the only input.We have applied this QHNC-MD method to Li, Na, K, Rb and Cs near the melting temperature. The structure factors, thus obtained, show excellent agreements with experimental data observed by X-ray and/or neutron scattering.