First-principles calculations of hyperfine parameters with the all-electron mixed-basis method

Within density functional theory, an efficient and accurate method for calculating and analyzing hyperfine parameters has been developed. The so-called mixed-basis method expands the one-electron wave functions in terms of both localized nucleus-centered functions and plane waves and thereby affords an accurate representation for the spin density both in the immediate vicinity of the nucleus and in the bonding regions. The current method is compared with experiment and the best computational methods reported in the literature. The mixed-basis approach is shown to yield highly accurate isotropic and anisotropic hyperfine parameters with modest computational effort. The atom-centered radial representation of the potentials and spin densities allows us to analyze, within the context of density functional theory, the effect of the exchange interaction on the individual core levels in a physically transparent way.