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采用平面波赝势方法对菱铁矿FeCO3高压下的晶体结构, 电子构型和电子结构进行了第一性原理计算研究. 研究过程中考虑了菱铁矿FeCO3真实的反铁磁(AFM)自旋有序态, 模拟静水压环境, 从零压逐步加压到500 GPa. 在4050 GPa压力范围内, FeCO3发生了从高自旋(HS)AFM态到低自旋(LS) 非磁性(NM)态的磁性相变, 伴随着晶胞体积坍塌10.5%. FeCO3在相变前后均是绝缘体, 但是相变后的LS-NM态的Fe2+ 离子的3d电子局域化程度更强, 能隙随着压力的进一步增大而逐步增大, 离化程度更高, 直到500 GPa没有发生金属绝缘体相变.The crystal structure, electronic configuration and electronic structure of siderite FeCO3 are studied by first-principles calculations through the plane wave pseudo-potential method. The real antiferromagnetic (AFM) spin ordering state is considered. The pressure increases up to 500 GPa under hydrostatic pressure condition. FeCO3 transforms from high spin (HS) AFM state to low spin (LS) nonmagnetic (NM) state in a pressure range between 40 and 50 GPa, accompaned with a volume collapse of 10.5%. Siderite FeCO3 is insulating before and after the phase transition, but the 3d electrons of Fe2+ ions for the LS-NM state are more localized, The band gap increases with pressure increasing, and the LS-NM state moves into a more strong ionic state and no metal-insulator transition (MIT) occurs.
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Keywords:
- FeCO3/
- phase transition/
- ab initio study/
- high pressure
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