This talk was part of the Workshop on "Spin-Orbit Entangled Quantum Magnetism" held at the ESI September 23 -- 27, 2024.

Finding the magnetic ground state is truly challenging on a technical level. The energy difference between different magnetic configurations can be on the order of µeV. Moreover, the energy landscape of spin-density-functional theory (SDFT) has many local minima, making the calculation's starting point extremely important. On top of that, one has to ask how reliably the SDFT magnetic ground state corresponds to the experimental magnetic ground state, which integrally depends on the level at which exchange and correlation effects are considered. The Vienna ab-initio simulation package (VASP) [1] is a powerful tool to perform calculations from first principles. It offers various methods to characterize magnetic states at different levels of approximation.

This talk discusses how to choose the initial guess for the magnetic configuration using the cluster multipole expansion [2,3]. Furthermore, it provides an overview of features in VASP with a focus on the spin degrees of freedom, some practical tips and tricks, and a sneak peek at upcoming features.

[1] https://www.vasp.at
[2] M.-T. Huebsch, T. Nomoto, M.-T. Suzuki, and R. Arita, Phys. Rev. X 11, 011031 (2021)
[3] M.-T. Huebsch, Nat. Rev. Phys. 5, 202 (2023)