Comparative study of magnetic exchange parameters and magnon dispersions in NiO and MnO using different first-principles methods

Magnons play a crucial role in explaining the behavior of magnetic materials and can lead to key technological applications. However, it is challenging to accurately model these in transition-metal compounds using methods based on density-functional theory (DFT) with (semi-)local functionals, due to the large self-interaction errors for d electrons. Here, we conduct a comparative analysis of the exchange parameters and magnon dispersions in NiO and MnO using three first-principles approaches, all applied to the same DFT+U ground state with Hubbard U computed from first principles using density-functional perturbation theory [1]. Two of these methods calculate the exchange parameters directly, one via total-energy differences and the other via the magnetic force theorem. From the parameterized Heisenberg Hamiltonian, we compute the magnon dispersions using linear spin-wave theory. The third approach is based on time-dependent density-functional theory with Hubbard correction [2] and probes directly the spin-spin susceptibility. This study contributes to the broader effort of evaluating the accuracy of first-principles methods for magnetic materials.

[1] I. Timrov et al., Phys. Rev. B 98, 085127 (2018)

[2] L. Binci et al., arXiv:2409.19504