From lattice dynamics to heat transport: Ab initio studies of β-FeSi2

Understanding how atomic vibrations determine heat transport is essential for the development of modern semiconductor and thermoelectric materials. Using advanced ab initio methods, lattice dynamics, phonon interactions, and thermal transport properties of β-FeSi₂ are investigated across a wide temperature range. Particular attention is devoted to anharmonic effects and their impact on vibrational properties, Raman spectra, and lattice thermal conductivity.
The study demonstrates that strong anharmonic renormalization of selected optical phonon modes is crucial for reproducing experimentally observed Raman linewidths and their temperature dependence. In addition, the relationship between crystal structure, phonon scattering, and anisotropic heat transport is analyzed. The obtained results provide microscopic insight into the mechanisms governing thermal transport in complex materials and show good agreement with available experimental data.