Theoretical investigation on the structural phase transition, elastic properties and hardness of RhSi under high pressure

We have carried out a systematic study on the structural phase transition, elastic properties and hardness of B31 and B20-phase RhSi under high pressure by first-principles calculations using the pseudopotential plane-wave method. The calculated values at zero pressure are in good agreement with experiments and similar theoretical calculations. Among them, the mechanism of the high pressure induced structural phase transition of RhSi has been studied in a detailed fashion. Under compression, the theoretical calculations show that RhSi will undergo a structural phase transition from B31-phase to B20-phase at 5.59 GPa. Based on the semiempirical method of the evaluation of covalent crystal, the hardness Hν of RhSi is estimated under high pressure. Remarkably, the theoretical results suggest that at zero pressure, the hardness value of B31-RhSi is 14.8 GPa and that of B20-RhSi is 19.0 GPa.