A LOCAL-DENSITY FORMULATION FOR NMR PARAMETERS IN METALS

The local-density approximation to the expression for the generalized complex spin susceptibility is used to treat simultaneously the effect s of core polarization and of susceptibility enhancement on the Knight shift and on the nuclear spin-lattice relaxation rate in metals. The resulting equations can be considered as refinements of the Yafet-Jacc arino (YJ) theory for transition metals, and retain the structure of a sum of terms related to partial densities of states at the Fermi leve l. The original YJ theory correctly identified the importance of core polarization, but was unable to provide good fits to experimental data in transition metals (specifically Pt and Pd). To obtain satisfactory agreement, later workers found it necessary to introduce empirically factors taking account of enhancement effects. This paper provides a t heoretical basis for doing so.