Ab initio Modeling of Phonons in the Family of Quasi-One-Dimensional Antiferromagnets AFeX2

A review of the recent development in ab initio calculations of the vibrational properties of quasi-one-dimensional (1D) antiferromagnets with AFeX2 structure is presented. Density functional theory (DFT + U) was applied to calculate the phonon modes specific to each element in the structure and the corresponding partial density of states (PDOS). The calculations revealed a strongly non-Debye phonon DOS. Using these results, the nuclear inelastic scattering spectra, temperature dependence of the Lamb-Mössbauer factor, infrared (IR) absorption strength, and phonon-specific heat were derived by direct summation over the phonon modes. The calculations demonstrate good agreement with the experiments and pave the way for understanding the anomalous magnetic properties of AFeX2 quasi-one-dimensional antiferromagnets at a quantitative level.