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Ab initioprediction of an order-disorder transition inMg2GeO4: Implication for the nature of super-Earth's mantles
Physical Review Materials ( IF 3.1 ) Pub Date : 2021-09-08 , DOI: 10.1103/physrevmaterials.5.093604
Koichiro Umemoto 1, 2 , Renata M. Wentzcovitch 3, 4
Affiliation  

Here we present an ab initio prediction of an order-disorder transition (ODT) from a I4¯2d-type to Th3P4-type phase in the cation sublattices of Mg2GeO4, a post-post-perovskite phase. This uncommon type of prediction is achieved by carrying out a high-throughput sampling of atomic configurations in a 56-atom supercell followed by a Boltzmann ensemble statistics calculation. Mg2GeO4 is a low-pressure analog of I4¯2d-type Mg2SiO4, a predicted major planet-forming phase of super-Earths' mantles. Therefore, a similar ODT is anticipated in I4¯2d-type Mg2SiO4 as well, which should impact the internal structure and dynamics of these planets. The prediction of this Th3P4-type phase in Mg2GeO4 further enhances the relationship between the crystal structures of Earth/planet-forming silicates and oxides at extreme pressures and those of rare-earth sesquisulfides at low pressures.

中文翻译:

Mg2GeO4 有序-无序转变的从头预测:对超级地球地幔性质的影响

在这里,我们提出了对有序-无序转变(ODT)的从头预测一世4¯2d-输入到 34阳离子亚晶格中的 - 型相 24,后钙钛矿相。这种不常见的预测是通过在 56 个原子的超级单元中对原子配置进行高通量采样,然后进行 Boltzmann 集成统计计算来实现的。24 是低压模拟 一世4¯2d-类型 24,预测的超级地球地幔的主要行星形成阶段。因此,预计类似的 ODT一世4¯2d-类型 24同样,这应该会影响这些行星的内部结构和动力学。这个预测34-输入阶段 24 进一步增强了极端压力下地球/行星形成硅酸盐和氧化物的晶体结构与低压下稀土倍半硫化物的晶体结构之间的关系。
更新日期:2021-09-08
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