Ab initio calculations of adiabatic magnon spectra using the atomic-sphere approximation for the spin direction

摘要

The frozen-magnon calculations of the adiabatic spin-wave spectra, which are often based on the atomic-sphere approximation for the spin directions (spin-ASA), are revisited. There are two complications arising from the spin-ASA: The atomic magnetic moments are not necessarily parallel to the local spin-quantization axes of the spin-ASA, and there may be additional torques acting on the magnetic moments. It is shown that the spin-wave energies obtained from spin-ASA calculations are very similar to those of full-spin calculations if these two complications are taken into account properly.