Phase relations in one of the key petrological systems, CaSiO₃, have been comprehensively investigated for the first time in the pressure range 0–100 GPa and temperatures 0–2500 K within the density functional theory using the method of lattice dynamics in the quasi-harmonic approximation. The results showed that at atmospheric pressure and 0 K CaSiO₃ is stable in the wollastonite structure, which above 1250 K transforms to the high-temperature pseudowollastonite modification. Above a pressure of 4 GPa, CaSiO₃ is stable in the breyite structure. The phase equilibrium curve has a negative slope of dP/dT = –0.6 MPa/K. At 8 GPa, CaSiO₃ decomposes into an assemblage of Ca₂SiO₄-larnite and titanite-structured CaSi₂O₅. The phase equilibrium curve has a positive slope of dP/dT = 1.35 MPa/K. At a pressure of 13 GPa, Ca₂SiO₄-larnite reacts with CaSi₂O₅, forming a phase with a perovskite-like structure – CaSiO₃-perovskite. The pressure of this phase transition is practically independent of temperature. In the low-temperature region, Ca-perovskite is stable in the tetragonal modification CaSiO₃-I4/mcm. Above 340 K at 13 GPa, Ca-perovskite is stable in the cubic modification CaSiO₃-\(Pm\bar {3}m.\) The phase transition temperature increases to 755 K with pressure increase to 100 GPa. The thermodynamic parameters were also calculated for the first time for wollastonite, pseudowollastonite, and titanite-structured CaSi₂O₅.

在密度泛函理论中，使用准晶格动力学方法，首次在 0-100 GPa 压力范围和 0-2500 K 温度范围内全面研究了其中一个关键岩石系统 CaSiO _{3 的相关}系。谐波近似。结果表明，在常压和0 K CaSiO ₃在硅灰石结构中是稳定的，在1250 K以上转变为高温假硅灰石改性。在 4GPa 以上的压力下，CaSiO ₃在布雷氏石结构中是稳定的。相平衡曲线的负斜率为dP/dT = –0.6 MPa/K。在 8 GPa 时，CaSiO ₃分解成 Ca ₂ SiO的集合₄ -larnite和钛铁矿结构的CaSi ₂ O ₅。相平衡曲线的正斜率为dP/dT = 1.35 MPa/K。在 13 GPa 的压力下，Ca ₂ SiO ₄ - 钙钛矿与CaSi ₂ O ₅反应，形成具有类似钙钛矿结构的相 - CaSiO ₃ -钙钛矿。这种相变的压力实际上与温度无关。在低温区域，Ca-钙钛矿在四方改性CaSiO ₃ - I 4/ mcm 中是稳定的。在 13 GPa 下高于 340 K，Ca-钙钛矿在立方变体 CaSiO _{3 中}是稳定的-\(Pm\bar {3}m.\)随着压力增加到 100 GPa，相变温度增加到 755 K。还首次计算了硅灰石、假硅灰石和钛石结构的 CaSi ₂ O ₅的热力学参数。