Berlin 2024 – scientific programme

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MA: Fachverband Magnetismus

MA 17: Computational Magnetism II

MA 17.5: Talk

Tuesday, March 19, 2024, 10:30–10:45, EB 202

High-throughput calculation of magnetic exchange interactions using DFT — •Jan Priessnitz and Dominik Legut — IT4Innovations, VSB-TU Ostrava, Ostrava, Czechia

Ab-initio calculation of magnetic properties is an invaluable tool in development of novel magnetic materials. Magnetism in these materials can often be modeled using the classical Heisenberg model, with exchange interaction being the most significant term, determining the ground state magnetic ordering as well as critical temperature, magnon spectrum, etc. Knowing the exchange interactions is a prerequisite for larger-scale spin-dynamic or micromagnetic calculations.

Exchange interactions are usually calculated via density functional theory (DFT), either through energy variation of the ground state (Green's functions), or by calculating the total energies of multiple magnetic configurations and fitting them into the Heisenberg model Hamiltonian. Neither method is completely foolproof, limiting the high-throughput use case.

In this talk, I'm going to focus on the total energy method, presenting a new approach for selecting a suitable set of excited magnetic configurations, including an algorithm that can efficiently traverse the exponentially-growing magnetic configuration space. This improvement allows us to use the total energy method even in otherwise difficult cases, e. g., calculating long-range interactions in metallic systems.

Furthermore, I'll introduce OstravaJ, a Python package that fully automates the exchange interaction calculation, employing in principle any non-collinear electronic structure DFT code, e.g. VASP.

Keywords: exchange interaction; spin-density functional theory; Heisenberg model; ab initio