金属锇超高压结构的理论研究

First-principles studies of crystal structures of osmium under high pressure

本文采用基于从头算演化理论的晶体结构预测方法,对过渡金属锇(Os)的高压结构进行了系统研究.结果表明,在0～1000 GPa压力范围内,金属Os一直保持六角密堆结构(hcp),没有发生结构相变,排除了前人提出的hcp到ω相变的可能.我们深入利用赝势平面波方法和全电子缀加波方法对ω相(P6/mmm)及hcp相进行了优化,并比较了能量随体积(压强)的变化关系,两种方法均证实了我们的结论.

Using ab initio evolutionary algorithm for crystal structure prediction, we have extensively explored crystal structures of Os under pressures in the range of 0-1000 GPa. Our theoretical prediction supports that elemental Os maintains the hcp structure in the whole pressure range studied and there is no phase transition under high pressure. This ruled out the earlier proposed high pressure ω phase. We have optimized the structures of hcp phase and ω phase using the pseudopotential plane-wave method and all-electron projector augment wave method within density functional theory, respectively. Both methods support our conculsion. The resulting E-V plots from both methods suggest that the hcp-Os is thermodynamic more stable in the studied pressure range of 0-1000 GPa.