Augmented-Plane-Wave Calculations of the Electronic Structure of Intermetallic Compounds YCu and YZn

In order to understand the electronic structure of the rare-earth intermetallic compounds RX, where $X=Cu,{{0ex}{0ex}}Ag,{{0ex}{0ex}}Au{{0ex}{0ex}}or{{0ex}{0ex}}Zn,{{0ex}{0ex}}Cd{{0ex}{0ex}}and R$ is a rare-earth element, the energy bands of the isomorphous compounds YCu and YZn have been calculated by the augmented-plane-wave method along different symmetry directions. The calculated Fermi energies for YCu and YZn are +0.42 and +0.47 Ry, respectively. The densities of states N(EF) at the Fermi level are obtained as 1.9±{}0.2 and 2.35±{}0.2 electrons/eV unit cell for YCu and YZn, respectively. This value for YCu is in good agreement with the experimental value of 1.32 electrons/eV unit cell obtained from specific-heat measurements. Also, the calculated change of density of states near the Fermi level is in the same direction as that obtained from specific-heat results on YCu substituted with small quantities of Ni or Zn. The implications of the calculated energy bands are discussed.