Effect of Core Polarization on Knight Shift and Relaxation Time in Metallic Cadmium

The core-polarization contributions to spin density in cadmium have been obtained using the moment-perturbed (MP) procedure and leads to increases of 10 and 17% in the isotropic Knight shift (Kₛ) and the relaxation rate (T₁T)^-1 at 0^∘{}K. The core-polarization effect is dominated by the s part of the wave functions of the conduction electrons on the Fermi surface, and therefore produces only a small departure (1.8%) of the Korringa ratio, R=(Kₛ²T₁T)ₑₓₚₜ(Kₛ²T₁T)ideal. Additionally, the small importance of the p-type core polarization indicates that the p component of the conduction-electron wave function has no significant influence on the Knight shift. A comparison of our theoretical results for Kₛ and (T₁T)^-1 leads to empirical enhancement factors of ηₛ=1.89 and ηM=3.10, which are factors 1.6 and 2.4 larger than the predictions from the current-exchange enhancement theories for susceptibility. Possible sources for the origin of this discrepancy are discussed.