Calculation of the exchange constants of the Heisenberg model in the plane-wave based methods using the Green's function approach

TL;DR

This paper introduces a Green's function and Wannier function-based method to calculate exchange constants in the Heisenberg model within plane-wave frameworks, enabling detailed analysis of magnetic interactions in various materials.

Contribution

The paper presents a novel computational scheme combining Green's functions and Wannier functions for calculating exchange parameters in plane-wave methods, validated on multiple magnetic materials.

Findings

Accurately computed exchange constants for NiO, FeO, Li2MnO3, and KCuF3.

The method explains pressure effects on the Néel temperature in FeO.

Li2MnO3 identified as a Slater insulator with specific magnetic properties.

Abstract

An approach to compute exchange parameters of the Heisenberg model in plane-wave-based methods is presented. This calculation scheme is based on the Green's function method and Wannier function projection technique. It was implemented in the framework of the pseudopotential method and tested on such materials as NiO, FeO, Li2MnO3, and KCuF3. The obtained exchange constants are in a good agreement with both the total energy calculations and experimental estimations for NiO and KCuF3. In the case of FeO our calculations explain the pressure dependence of the N\'eel temperature. Li2MnO3 turns out to be a Slater insulator with antiferromagnetic nearest-neighbor exchange defined by the spin splitting. The proposed approach provides a unique way to analyze magnetic interactions, since it allows one to calculate orbital contributions to the total exchange coupling and study the mechanism of the exchange coupling.