ELECTRONIC-STRUCTURES OF DISORDERED AG-MG ALLOYS

We have calculated the electronic structures of the valence bands in a series of alpha-phase (disordered fcc) Ag-Mg alloys over the range 0- 30 at. % Mg using the Korringa-Kohn-Rostoker method within the coheren t potential approximation (KKR-CPA). We find that the variation of the equilibrium lattice constant with composition is in good agreement wi th experimental measurements. The bandwidth of the Ag-related d states decreases with the addition of Mg although the position of the bottom of the band remains roughly fixed in energy with respect to the Fermi level; an observation that is consistent with photoemission measureme nts. The electronic spectral densities are very sharply peaked at the Fermi energy with widths that are < 1% of the Brillouin zone dimension and so the Fermi surfaces of the alloys are well defined throughout t he zone. The radius of the neck at the L point and the belly radii in the Gamma X and Gamma K direction increases approximately linearly wit h increasing Mg content. Taking into account some previous work on the origin of short range order in Ag-rich alloys, we conclude that the l ocal-density approximation KKR-CPA method provides a realistic descrip tion of the electronic structure in alpha-phase ($) under bar Ag-Mg al loys.