热力学相关压力下Fe杂质对MgO影响的第一性原理研究
First-principles study of the effect of Fe impurities in MgO at geophysically relevant pressures
摘要：
采用自相互作用修正的局域自旋密度（SIC-LSD）理论和交换关联能的标准GGA处理方法研究了MgO中Fe杂质的磁矩坍缩. Mg_{1-x} Fe_xO系统被认为是地球下地幔中第二丰富的矿物。我们证实了实验发现的铁浓度的临界压力的增加。我们用标准GGA对固定Fe原子浓度的计算表明，不同的Fe原子排列方式可以显著地改变高自旋（HS）到低自旋（LS）的跃迁压力.这可以解释实验发现的宽过渡区。结果表明，Mg$_（1-x）Fe_xO的HS-LS相变为一级相变。我们发现，SIC-LSD未能预测的二价铁的配置作为最低的能量配置，并讨论了可能的原因。
英文摘要：
The self-interaction corrected local spin density (SIC-LSD) formalism and the standard GGA treatment of the exchange-correlation energy have been applied to study the collapse of the magnetic moment of Fe impurities in MgO. The system Mg_{1-x}Fe_xO is believed to be the second most abundant mineral in the Earth's lower mantle. We confirm the experimentally found increase of the critical pressure upon iron concentration. Our calculations using standard GGA for a fixed Fe concentration show that different arrangements of Fe atoms can remarkably shift the transition pressure of the high spin (HS) to low spin (LS) transition. This could explain the experimentally found broad transition regions. Our results indicate that the HS-LS transition in Mg$_{1-x}Fe_xO is first order. We find that SIC-LSD fails to predict the divalent Fe configuration as the lowest energy configuration and discuss possible reasons for it.
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