Toward Routine Gauge-Including Projector Augmented-Wave Calculations for Metallic Systems: The Case of ScT₂Al (T = Ni, Pd, Pt, Cu, Ag, Au) Heusler Phases

We use the gauge-including projector augmented-waves (GIPAW) method to report, for the first time, theoretical ²⁷Al Knight shifts in metallic systems other than metallic Al. We consider metallic Al and a set of six intermetallic compounds, for which experimental chemical shifts were recently made available in the literature. The orbital and spin components of the chemical shielding tensors are computed from the same ground-state spin-polarized electronic structure, converged under the influence of a uniform external magnetic field. A linear response formalism is used to compute the orbital part, while the spin part is approximated by the linear relationship between the external field and the Fermi contact contribution to the induced magnetic hyperfine field at the nuclear position. Core spin-polarization effects are taken into account by means of a perturbative approach. Our results show that the GIPAW approach yields reasonably acceptable chemical shifts with affordable k-meshes in the irreducible Brillouin zone, enabling separation between contributions to metallic shifts from the electron orbital and from the electron spin susceptibilities.