A first-principles study of bcc chromium beyond the generalized gradient approximation (GGA)

TL;DR

This paper investigates the magnetic properties of bcc chromium using advanced density functional theory methods beyond GGA, highlighting the limitations of current functionals in predicting its complex spin-density wave ground state.

Contribution

It provides a comprehensive DFT analysis of bcc Cr with meta-GGA functionals, revealing their overestimation of magnetic moments and the need for improved functionals for magnetic systems.

Findings

Meta-GGA functionals overestimate magnetic moments in bcc Cr.

TPSS functional best approximates GGA results for bcc Cr.

Current functionals struggle to accurately predict the SDW ground state.

Abstract

The study of magnetism in transition metals is a cornerstone in understanding complex electronic and magnetic interactions in condensed matter systems. Among transition metal elements, body-centered cubic (bcc) chromium stands out because of its spin-density wave (SDW) ground state, posing a long-standing challenge for density functional theory (DFT). Conventional functionals, such as the generalized-gradient approximation (GGA) and the local-density approximation (LDA), fail to predict this experimentally observed incommensurate SDW as the ground state. In this study, we present a comprehensive DFT analysis of bcc Cr employing GGA and a variety of meta-GGA functionals. We evaluated total energies, structural parameters, and magnetic properties across a wide range of SDW wave vectors. Our results show that all meta-GGA functionals overestimate the local magnetic moments and enhance the nodal magnetic frustration, destabilizing the SDW state relative to the commensurate antiferromagnetic (AF) configuration. Tao-Perdew-Staroverov-Scuseria (TPSS) yields results closest to those of the GGA, thus providing the most adequate description of bcc Cr among the meta-GGA functionals. These results emphasize the need for the further development of non-local or hybrid functionals tailored for complex magnetic systems.