title: Electronic structure of Li2Ga and Li9Al4, two solids containing infinite and uniform zigzag chains.
abstract: The electronic structure of inorganic solids such as Li(2)Ga and Li(9)Al(4) containing infinite zigzag homoatomic chains is discussed. It is shown that Li(2)Ga, a solid for which a Zintl-type electron-counting approach would suggest that a half-filled pi-type band occurs as in trans-polyacetylene, is really a three-dimensional solid with strong covalent interchain connections and small effective charge transfer. The zigzag chains do not play a dominant role as far as the electronic structure near the Fermi level is concerned, and there is no reason for the occurrence of a Peierls distortion despite the possible analogy with trans-polyacetylene. It is suggested that even assuming that a Zintl-type approach is appropriate for electron counting purposes, the infinite zigzag chains in this compound and those in trans-polyacetylene are not isolobal. The bonding in Li(9)Al(4) and Li(2)Ga is very similar, and both phases are predicted to be stable three-dimensional metals.
authors.affiliation: Departament de Química Física and Centre de Recerca en Química Teorica, Universitat de Barcelona, Diagonal 647, 08028 Barcelona, Spain. alemany@qf.ub.es
authors.forename: Pere
authors.initials: P
authors.lastname: Alemany
authors.forename: Miquel
authors.initials: M
authors.lastname: Llunell
authors.forename: Enric
authors.initials: E
authors.lastname: Canadell