用LDA +U研究正铁氧体LuFeO_3的体积和自旋坍缩
Study of the volume and spin collapse in orthoferrite LuFeO_3 using LDA+U
摘要：
稀土（R）正铁氧体RFeO_3表现出与自旋坍缩有关的大体积转变。我们在这里介绍从头计算LuFeO_3。我们表明，考虑到Fe-3d电子之间的强关联是必要的。事实上，与LDA+U的方法在投影增强波（PAW），我们能够描述的同构相变在50 GPa，以及在过渡和相当大的减少的磁矩的铁离子的体积不连续性为6.0%。我们进一步研究了U和J的变化的影响，并发现这些参数的转变压力的线性依赖。我们给出了一个解释J的非直观效果。这强调了需要正确确定这些参数，特别是当LDA+U应用于系统（例如在地球物理调查）的过渡压力是先验未知的。
英文摘要：
Rare earth (R) orthoferrites RFeO_3 exhibit large volume transitions associated with a spin collapse. We present here ab initio calculations on LuFeO_3. We show that taking into account the strong correlation among the Fe-3d electrons is necessary. Indeed, with the LDA+U method in the Projector Augmented Wave (PAW), we are able to describe the isostructural phase transition at 50 GPa, as well as a volume discontinuity of 6.0% at the transition and the considerable reduction of the magnetic moment on the Fe ions. We further investigate the effect of the variation of U and J and find a linear dependence of the transition pressure on these parameters. We give an interpretation for the non-intuitive effect of J. This emphasizes the need for a correct determination of these parameters especially when the LDA+U is applied to systems (e.g in geophysical investigations) where the transition pressure is a priori unknown.
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