Atomistic study of lattice structure of BiScO3

The total energies and lattice structures of one paraelectric and two ferroelectric phases of BiScO3 (BSO) were obtained through first principles calculations at zero temperature. The structural instability and phase transition of this material with 5-atom per unit cell was revealed by the simultaneous existence of zone-center and zone-boundary soft phonon modes in phonon dispersion relations. Based on the first principles calculations, a simple rigid-ion pair potential model was developed by fitting of total energy. This atomistic model reproduced the crucial ferroelectric properties of BSO and enabled the molecular dynamics (MD) simulations to be performed for the investigation of BSO on the ground state at non-zero temperature. A monoclinic phase was discovered for BSO, which is consistent with experimental results.