On the structure and compressibility of CaSiO3 perovskite
On the structure and compressibility of CaSiO3 perovskite
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DOI：
10.1029/2001gl013523
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发表时间：
2002-02
影响因子：
5.2
通讯作者：
S. Akber‐Knutson;Mark S. T. Bukowinski;J. Matas
中科院分区：
文献类型：
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作者：
S. Akber‐Knutson;Mark S. T. Bukowinski;J. Matas
使用基于密度泛函数的变诱发呼吸（VIB）方法在高压下测定了CaSiO3钙钛矿的状态方程和结构，并对短程Si - O相互作用进行了小的参数化共价修正。我们的热校正室温状态参数方程（V0 = 45.90±0.02 Å， K0 = 228±2 GPa, K′= 4.3±0.1）与近静压数据以及最近基于第一性原理方法的计算结果非常吻合。我们研究了四方、正交和三斜结构，并比较了它们在下地幔压力下相对于立方结构的稳定性。我们发现CaSiO3的正交钙钛矿结构是所有地幔压力下的热力学稳定相。在静态条件下，正交晶格和立方晶格之间的结构和能量差异很小，并且随着压力的增加而略有增加。因此，立方结构在较低的地幔温度下可能是热力学稳定的。
The equation of state and structure of CaSiO3 perovskite are determined at high pressures using the density‐functional‐based Variationally Induced Breathing (VIB) method, modified with a small, parameterized covalent correction to the short‐range Si‐O interaction. Our thermally corrected room temperature equation of state parameters (V0 = 45.90 ± 0.02 Å, K0 = 228 ± 2 GPa, K′ = 4.3 ± 0.1) are in very good agreement with near‐hydrostatic compression data as well as recent calculations based on first‐principles methods. We examined the tetragonal, orthorhombic, and triclinic structures, and compared their stabilities relative to the cubic structure at lower mantle pressures. We found that the orthorhombic perovskite structure of CaSiO3 is the thermodynamically stable phase at all mantle pressures. The structural and energy differences between the orthorhombic and cubic lattices under static conditions are small, and increase only slightly with pressure. Consequently, the cubic structure may be thermodynamically stable at lower mantle temperatures.