1987 Fiscal Year Final Research Report Summary
Electronic energy band structure calculations for uranium compounds by a relativistic APW method
| Project/Area Number |
60540200
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
固体物性
|
|---|
| Research Institution | Niigata University |
|---|
Principal Investigator |
HASEGAWA Akira General Education Department, Niigata University; Professor, 教養部, 教授 (40004329)
|
|---|
| Project Period (FY) |
1985 – 1987
|
| Keywords | Band theory / Density functional theory / Uranium compounds / Cerium compounds / Fermi surface / 4f electrons / 5f電子 |
|---|
| Research Abstract |
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.
|
