压缩轻稀土中4f矩的屏蔽和离域
The screening of 4f moments and delocalization in the compressed light rare earths
摘要：
利用动力学平均场论结合局域密度近似计算了压缩Ce（n=1），Pr（n=2）和Nd（n=3）金属的自旋和电荷极化率以及4f^n，4f ^{n-1}和4f^{n+1}组态权重.在环境和更大的体积下，这些三价稀土被钉扎在尖锐的4f^n构型上，它们的4f矩假定为原子极限值，没有被屏蔽，并且4f电荷波动很小，表明费米能级附近的f态密度很小。在压缩下，有戏剧性的屏蔽的时刻和相关的增加，在这两个4f的电荷波动和静电荷的敏感性。这些变化与4f^{n-1}组态权重的增长相一致，这被认为是比4f^{n+1}权重更好的离域度量，4f ^{n+1}权重被6s，6p带上升导致的4f电子数量增加所损害。这一过程是连续的，并作为体积的函数而延长，三种稀土元素之间具有惊人的相似性，除了对较重成员的影响缓和并转向较小的体积。所观察到的α-γ崩溃Ce发生在大体积的一半，这一演变，Pr类似物在较小的体积，和Nd没有崩溃。
英文摘要：
Spin and charge susceptibilities and the 4f^n, 4f^{n-1}, and 4f^{n+1} configuration weights are calculated for compressed Ce (n=1), Pr (n=2), and Nd (n=3) metals using dynamical mean field theory combined with the local-density approximation. At ambient and larger volumes these trivalent rare earths are pinned at sharp 4f^n configurations, their 4f moments assume atomic-limiting values, are unscreened, and the 4f charge fluctuations are small indicating little f state density near the Fermi level. Under compresssion there is dramatic screening of the moments and an associated increase in both the 4f charge fluctuations and static charge susceptibility. These changes are coincident with growing weights of the 4f^{n-1} configurations, which it is argued are better measures of delocalization than the 4f^{n+1} weights which are compromised by an increase in the number of 4f electrons caused by rising 6s, 6p bands. This process is continuous and prolonged as a function of volume, with strikingly similarity among the three rare earths, aside from the effects moderating and shifting to smaller volumes for the heavier members. The observed alpha-gamma collapse in Ce occurs over the large-volume half of this evolution, the Pr analog at smaller volumes, and Nd has no collapse.
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