Molecular cluster studies of binary alloys: LiAl

The electronic structure of the ordered Zintl ($B32$) phase of LiAl has been studied in a molecular-cluster model within the framework of the Hartree-Fock-Slater theory. ${\mathrm{Li}}_{5}$${\mathrm{Al}}_{4}$ and ${\mathrm{Al}}_{5}$${\mathrm{Li}}_{4}$ clusters were embedded in a potential field representative of the alloy environment; energy levels and wave functions were obtained by self-consistent iteration. Density-of-states and charge-density results are used to interpret NMR and electrical-conductivity studies. The case of a single Li vacancy was also treated, and discussed in the light of positronannihilation data.