NMR Shielding in Metals Using the Augmented Plane Wave Method.

Area of Science:

• Solid-state physics
• Quantum chemistry
• Materials science

Background:

• Accurate calculation of magnetic shielding is crucial for understanding NMR spectra in metals.
• Previous methods often struggled to consistently incorporate both spin and orbital contributions, especially for transition metals.

Purpose of the Study:

• To develop and present a consistent theoretical framework for calculating solid-state NMR magnetic shielding in metals.
• To investigate the contributions of both orbital and spin responses to NMR shielding, particularly in transition metals.

Main Methods:

• Density Functional Theory (DFT) combined with the augmented plane wave (APW) approach.
• Implementation within the WIEN2k computational code.
• Inclusion of all-electron self-consistent treatment for core states and consideration of induced spin-polarization.

Main Results:

• Calculations successfully incorporate both orbital and complete spin responses for NMR magnetic shielding.
• For transition metals, core s-states are polarized in the opposite direction by the induced magnetic moment of d-electrons.
• First-principle calculations yield converged and reliable results, surpassing previous estimations of accuracy.
• Large k-meshes and Fermi-broadening are essential for achieving converged results.

Conclusions:

• Both spin and orbital components of NMR shielding are necessary for accurate reproduction of experimental shifts in metallic systems, especially transition metals.
• The developed method enables routine and reliable NMR calculations for a wide range of metallic systems.
• This work advances the predictive power of computational methods in solid-state NMR spectroscopy.