Electronic structure beyond the generalized gradient approximation for Ni$_2$MnGa

TL;DR

This paper investigates the electronic structure of Ni$_2$MnGa beyond the GGA approximation using advanced density functional theory methods, analyzing phase stability, Fermi surface, and phonon dispersion with various exchange-correlation functionals.

Contribution

It introduces a procedure to mitigate overestimation of magnetization and nesting vector in SCAN meta-GGA calculations for Ni$_2$MnGa.

Findings

Different exchange-correlation functionals affect phase stability predictions.

SCAN meta-GGA provides improved electronic structure descriptions.

A parametric correction reduces overestimated magnetization.

Abstract

The stability of the nonmodulated martensitic phase, the austenitic Fermi surface and the phonon dispersion relations for ferromagnetic Ni$_2$MnGa are studied using density functional theory. Exchange-correlation effects are considered with various degrees of precision, starting from the simplest local spin density approximation (LSDA), then adding corrections within the generalized gradient approximation (GGA) and finally, including the meta-GGA corrections within the strongly constrained and appropriately normed (SCAN). We discuss a simple procedure to reduce a possible overestimation of magnetization and underestimation of nesting vector in SCAN by parametrically decreasing self-interaction corrections.