The generalized susceptibility, χ(q), in Pd and Pt for q along the , , , and  directions was determined from their APW and RAPW energy band structures, respectively, using the analytic tetrahedron linear energy scheme of Rath and Freeman. The band structures were previously found to yield Fermi surface radii, temperature dependencies of the static magnetic susceptibility, χ(T), resistivity, and a spin lattice relaxation, T1T, in very good agreement with experiment. In the χ(q) calculations, we used 2048 tetrahedra in 1/48th irreducible BZ and the energy eigenvalues for bands 4, 5, and 6 which cross the Fermi energy as fitted to a Fourier series representation. The intraband parts of χ(q) at q = 0 for both metals are found to agree with the density of states at the Fermi energy to without 0.5%. Our results show that the dominant contribution to χintraarises from the dominant band 5 whose "jungle-gym" FS has strong nesting features; the main peak for Pd occurs at the same q value (= 0.65π/a) for q along the [0q0], [q, q, 0], and [q, q, q] directions. The locus of this main peak is a square in the (0, 0, 1) plane. The maximum of χintrafor q along the  and  directions are 23% and 13%, respectively, higher than the value of χ(q) at q = 0. For q along the  and  directions, the peak is, however, lower than the value of χintraat q = 0. Hence, while phonon anomalies are predicted for the  and  directions, no anomaly is predicted for either the  or  direction. The predicted q value for the  anomaly, q = 0.65π/a is close to the experimental value of ∼0.7 π/a. Although there may be a hint of an anomaly at 0.56  in the measurements, a more detailed investigation of this region is called for. For platinum, χintrafor q along the ,  and  directions has main peaks which occur at q = 0.68 π/a, 0.75 π/a, and 0.85 π/a, respectively. Here too, this main peak comes from the nesting of the jungle-gym Fermi surface which is not, however, as flat as that of palladium. Anomalies are predicted (although weaker in Pt than in Pd) along  and  but not along  and . The  anomaly is close to the measured q value (∼0.7-0.8 π/a). Also in agreement with experiment, we predict a weaker  anomaly for Pt than for Pd. In both Pd and Pt, weaker anomalies are predicted for the  direction than for the  direction. © 1979.
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