Molecular dynamics study of high-pressure polymorphs of BaCO₃

We report a computational study of BaCO3 at high pressure using molecular dynamics simulation based on a recent potential model. The first phase transition from the witherite to the post-aragonite phase is observed at 9.67 GPa with a resistance to shear along the [0 0 1] direction and a high compressibility in a direction perpendicular to the layers. This stable phase is also found through the variation of the bulk modulus, the shear moduli, and the compressional and shear wave velocities with pressure. A softening mode is noticed at a pressure around 10 GPa. The computed X-ray diffraction pattern of the post-aragonite phase at 16 GPa shows favorable agreement with the available experimental data.