Assessing the SCAN functional for itinerant electron ferromagnets

TL;DR

This paper evaluates the performance of the SCAN functional in density functional theory for transition metals Fe, Co, and Ni, revealing limitations in magnetic and structural property predictions compared to experimental data.

Contribution

The study provides a systematic assessment of the SCAN functional's accuracy for itinerant ferromagnets, highlighting its strengths and weaknesses.

Findings

SCAN performs well for bcc-Fe structural properties.

SCAN overestimates magnetic moments in Fe, Co, Ni.

3d states are shifted to lower energies with SCAN.

Abstract

Density functional theory is a standard model for condensed matter theory and computational material science. The accuracy of density functional theory is limited by accuracy of the employed approximation to the exchange-correlation functional. Recently, the so-called strongly constrained approprietly normed (SCAN) functional has received a lot of attention due to promising results for covalent, metallic, ionic, as well as hydrogen- and van der Waals-bonded systems alike. In this work we focus on assessing the performance of the SCAN functional for itinerant magnets by calculating basic structural and magnetic properties of the transition metals Fe, Co and Ni. We find that although structural properties of bcc-Fe seem to be in good agreement with experiment, SCAN performs worse than standard local and semilocal functionals for fcc-Ni and hcp-Co. In all three cases, the magnetic moment is significantly overestimated by SCAN, and the $3d$ states are shifted to lower energies, as compared to experiments.