Structure of the metallic ζ-phase of oxygen and isosymmetric nature of the ε-ζ phase transition:: Ab initio simulations
Structure of the metallic ζ-phase of oxygen and isosymmetric nature of the ε-ζ phase transition:: Ab initio simulations
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DOI：
10.1103/physrevb.76.064101
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发表时间：
2007-08-01
影响因子：
3.7
通讯作者：
Glass, Colin W.
中科院分区：
文献类型：
--
作者：
Ma, Yanming;Oganov, Artem R.;Glass, Colin W.
使用从头算演化方法的晶体结构预测，我们探索金属结构的氧在压力范围内的100-250 GPa。两个积极竞争的单斜结构的C2/c（4摩尔/细胞）和C2/m（8摩尔/细胞）被发现作为zeta-O-2的候选人。C2/m结构是我们的优选解决方案，提供稍低的焓和与实验X射线衍射（XRD）图案和拉曼频率更好的一致性。我们的理论预测支持ε-zeta转变的等对称性质，与基于粉末XRD测量的建议一致[Y. Akahama，Phys. Rev. Lett. 74，4690（1995）]。此外，我们发现，至少高达250 GPa，氧仍然是一个分子固体，在这个压力范围内没有后zeta相。
Using ab initio evolutionary methodology for crystal structure prediction, we explore metallic structures of oxygen at pressures in the range of 100-250 GPa. Two energetically competitive monoclinic structures of C2/c (4 mol/cell) and C2/m (8 mol/cell) were found as candidates for zeta-O-2. The C2/m structure is our preferred solution, providing slightly lower enthalpy and better agreement with experimental x-ray diffraction (XRD) pattern and Raman frequencies. Our theoretical prediction supports the isosymmetric nature of the epsilon-zeta transition, in accordance with the suggestion based on the powder XRD measurements [Y. Akahama , Phys. Rev. Lett. 74, 4690 (1995)]. Moreover, we find that at least up to 250 GPa, oxygen remains a molecular solid and there is no post-zeta-phase in this pressure range.