Direct and Core-Polarization Contributions to the Knight Shift in Metallic Aluminum

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Abstract
The Knight-shift calculation for aluminum metal is carried out using orthogonalized-plane-wave wave functions for the conduction electrons. The direct contribution is calculated to be 0.151%. The core-polarization correction to the Knight shift is obtained by the moment-perturbation method and is found to be 0.012%. The total calculated Knight shift is 0.163%, as compared with the experimental value of 0.168% obtained by Sagalyn and Hofmann. The good agreement between theory and experiment is in keeping with the anticipated small contribution from orbital effects. As a by-product, some useful conclusions are arrived at concerning the utility of the pseudopotential method for obtaining conduction-electron wave functions and the extension of the moment-perturbation procedure for studying core-polarization effects when more than one core state is involved.