Crystal structure and properties of barium thorate BaThO_3 from first principles

摘要

The phonon spectrum of cubic BaThO_3 with the perovskite structure is calculated from first principles within the density functional theory. The analysis of unstable modes in the phonon spectrum enables to determine the symmetry of all possible distorted phases, calculate their energies, and show that the ground-state structure of barium thorate is Pbnm. For this structure, the static and optical dielectric constants, elastic moduli, heat capacity, Raman spectra, and the energy band gap in the LDA and GW approximations are calculated. The possibility of the structural phase transitions in BaThO_3 is also discussed.