Crystal stabilities and electronic properties of thorium silicide under ambient conditions and high pressures from a first-principles study

The thorium compounds are prospective candidates for the next generation nuclear materials. Using the first-principles and particle swarm optimization methods, we have investigated structures and physical properties of four atomic ratios of thorium and silicon hybrids under various ranges from ambient pressure to 200 GPa. A series of new phases have been predicted and thermodynamics, mechanical stabilities, elastic properties, electronic properties and chemical bonds of all the stable structures have been studied in details. Furthermore, we utilize potential energy surface to investigate the vibration property of Si₂ dimer in Th₃Si₂. The result indicates that the Si₂ dimer in Th₃Si₂ compound have the similar vibration property as a free standing Si₂. This also means the silicon atoms do not have a strong interaction with thorium atoms in thorium silicide.