New insight into the structure of PuGaO3 from ab initio particle-swarm optimization methodology

Abstract

A systematic study of the phase stability, chemical bonding, and lattice dynamics properties of PuGaO₃ is performed by means of unbiased particle-swarm optimization techniques combined with first-principles calculations. Phase stability analyses, including total energy, formation enthalpy, mechanical stability, and lattice dynamics, indicate that the ground-state structure of PuGaO₃ at ambient pressure belongs to the space group Pnma. The fat-band dispersions and chemical bonding analysis suggest that Pnma PuGaO₃ is an indirect band gap semiconductor (2.46 eV at the PBEsol + U level) at the Γ point and the Pu–O and Ga–O bonds in Pnma PuGaO₃ are dominated by the ionic interactions. By examining the phonon spectra and phonon DOS, we provide a detailed insight into the lattice dynamics and thermodynamic properties of PuGaO₃. In addition, the infrared absorption and Raman scattering spectra of PuGaO₃ are predicted and further assigned at the center (Γ point) of the first Brillouin zone.