Theory of Hyperfine Properties of Beryllium and Magnesium Metals

作者：Puru Jena, Tara Prasad Das, S. D. Mahanti · 发表于：Physical review. B, Solid state · 年份：1970 · DOI：10.1103/physrevb.1.432 · 被引用次数：35 · 研究领域：Advanced Chemical Physics Studies、Rare-earth and actinide compounds、Inorganic Fluorides and Related Compounds

A detailed analysis of the hyperfine properties of the lighter group-II metals, beryllium and magnesium, has been carried out to understand the relation between the electronic structures of these hcp metals. The "lens" and "butterflies" of the magnesium Fermi surface have large $s$ character, leading to an appreciable value of the Knight shift ${K}_{s}$. In contrast, beryllium does not have these pieces of the Fermi surface, and this qualitatively explains the vanishingly small ${K}_{s}$ for beryllium. Core polarization (cp) plays an important role in explaining the experimental values of ${K}_{s}$. There is a basic difference between beryllium and magnesium as regards the cp contribution to the Knight shift (${K}_{\mathrm{cp}}$). For beryllium, ${{K}_{s}}^{\mathrm{cp},p}$, the $p$ part of the cp contribution is negative and this, together with a small direct contribution ${{K}_{s}}^{d}$, leads to a vanishingly small value for ${K}_{s}$ (0.7\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}3}$%), as compared to -0.25\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}2}$% obtained experimentally. Orbital effects are expected to explain the remaining discrepancy in beryllium. For magnesium, ${{K}_{s}}^{\mathrm{cp}}$ is roughly 38% of ${{K}_{s}}^{d}$, and the total theoretical value of ${K}_{s}$ is 0.0554%, compared to the experimental value of 0.112%. The uncertainties in the exchange enhancement of ${\ensuremath{\chi}}_{p}$ and the role of other contributions to ${K}_...