Crystal structure and properties of barium thorate BaThO3 from first principles

• The ground-state structure of BaThO3 is Pbnm.
• The physical properties of barium thorate are calculated.
• The structural phase transition can occur in BaThO3 slightly above 300 K.

The phonon spectrum of cubic BaThO3 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 BaThO3 is also discussed.