Structural and electronic properties of crystalline and molten Zintl phases: The Li-Ga system

We present a theoretical investigation of the structural and electronic properties of crystalline and molten Li-Ga alloys. The atomic structure of the liquid phases is determined by molecular dynamics, based on pseudopotential-derived interatomic forces. The electronic structure is calculated using the linear-muffin-tin-orbital (LMTO) method for the crystalline compounds LiGa, Li₃{Ga}₂$, and ${Li}₂$Ga, and using an LMTO-supercell approach for several liquid alloys. Our results demonstrate the validity of an extended Zintl principle. The bonding is dominated by the attractive potential of the Ga ions and may be described at least formally in terms of an electron transfer from Li to Ga. The atomic structure of the Ga sublattice in the crystalline compounds and the short-range Ga-Ga correlations in the melt, as well as the electronic structure, are found to be Ge-, As-, and Se-like with increasing Li concentration and an increasing number of electrons per Ga atom.