Ab initiomolecular-dynamics simulation of liquid Ga-Ge alloys

Abstract

We report the results of ab initio molecular-dynamics simulations of liquid Ga-Ge alloys at four different concentrations. The physical quantities studied include the partial structure factors, bond-angle distributions, self-diffusion coefficients, electronic density of states, and the electrical conductivity. The introduction of Ga causes a distinct reduction of the shoulder in the structure factor of pure $\mathcal{l}$-Ge. Correspondingly, the partial structure factors, pair correlation functions, and bond angle distribution functions all show behavior characteristic of simple liquid metals except at 80% Ge. The electronic density of states shows a behavior consistent with the structure: it evolves from having a distinct pseudogap at low concentrations of Ga to being almost free-electron-like for high Ga concentrations. The calculated behavior of the electrical conductivity agrees qualitatively with previous calculations based on the Faber-Ziman theory of liquid alloys. The self-diffusion coefficients ${D}_{\mathrm{G}\mathrm{e}\ensuremath{-}\mathrm{G}\mathrm{e}}$ and ${D}_{\mathrm{G}\mathrm{a}\ensuremath{-}\mathrm{G}\mathrm{a}}$ are consistent with previous calculations and available experiments for the pure liquids.