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Electronic energy band structure calculations for uranium compounds by a relativistic APW method

相对论APW法计算铀化合物的电子能带结构

基本信息

批准号：
60540200
负责人：
HASEGAWA Akira
金额：
$ 1.22万
依托单位：
Niigata University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1985
资助国家：
日本
起止时间：
1985 至 1987
项目状态：
已结题

项目摘要

Electronic energy band structures for typical uranium compounds were calculated using an itinerant model for f-electrons. One-electron potential was constructed based on the density-functional theory in a local-density approximation, and the energy bands were calculated by a relativistic augmented plane-wave method that takes into account the spin-orbit interaction. For the sake of comparison, band calculations were carried out also for typical cerium compounds by the same method.For the AuCu_3-type compounds which uranium forms with the elements of the group IV in the periodic table, such as USi_3 and UGe_3, the theoretical density of states at the Fermi lefel agrees quantitatively well with the experimental value derived from the low-temperature electronic specific heat constant, and the Fermi surface can explain reasonably well the observed de Haas-van Alphen effects. The agreement between theory and experiment is as good as those obtained for the 3d transition metals. However, band theory could not explain well experimental results for USn_3 and UPb_3.In CeSn_3, which is considered as a typical valence-fluctuation system, 4f electrons hybridise strongly with p states of Sn. Since the Fermi level, however, lies in the p bands, the density of states at the Fermi level cannot become very large. Therefore, anormalies due to 4f electrons in CeSn_3 are not sharp. In contrast, the Fermi level in CePd_3 is located near the botton in the f bands, and there exist small electron and hole Fermi surfaces in the 4f bands the block states on which consist dominantly with almost pure 4f character. Simple analysis suggests that these small Fermi surfaces may play an essential role in anomalous behaviours of the electrical resistivity of CePd_3.

用f电子巡回模型计算了典型铀化合物的电子能带结构。在局域密度近似下，基于密度泛函理论构造了单电子势，并用考虑自旋-轨道相互作用的相对论增广平面波方法计算了能带。为了便于比较，还用相同的方法对典型的Ce化合物进行了能带计算，对于铀与元素周期表中第IV族元素形成的AuCu3型化合物，如USi3和UGe3，费米能级的理论态密度与由低温电子比热常数得到的实验值定量地符合得很好，费米面可以很好地解释观察到的De Haas-van Alphen效应。理论与实验的吻合程度与3d过渡金属的结果相当。然而，能带理论不能很好地解释USn3和UPb3的实验结果。在CeSn3中，4f电子与锡的p态发生强烈的杂化。然而，由于费米能级位于p带，费米能级的态密度不可能变得很大。因此，CeSn3中4f电子引起的反常现象并不明显。而CePd_3中的费米能级位于f带的底子附近，在4f带存在小的电子和空穴费米面，其上的阻塞态主要具有纯4f特征。简单的分析表明，这些小的费米面可能在CePd_3的电阻率反常行为中起着重要作用。