Band-structure calculation of MBe₁₃(M=La, Ce, Th and U)

The one-electron energy band structures for LaBe 13 , CeBe 13 , ThBe 13 and UBe 13 were calculated by the self-consistent APW method with the local density approximation. It was found that the Be s(p) bands form wide valence bands below a pseudogap at 0.8 eV below the Fermi energy E F in UBe 13 ; and the Be p bands extend mostly above a pseudogap at 1.9 eV above E F in UBe 13 . Between these bands, there are M d-Be p mixed bands. In CeBe 13 and UBe 13 , the f bands are inserted among the d-p mixed bands. Due to the squeezing effect of the p-f mixings from both above and below the f bands, the f band widths in CeBe 13 and UBe 13 are very small, only 1 eV in UBe 13 , much narrower than the experimentally observed PES-BIS peak, indicating the importance of the many-body effect. In LaBe 13 and ThBe 13 , the f band widths are much larger, more than twice that in UBe 13 , due to the reversed p-f mixing effect. The p-f mixing parameters for these materials were also evaluated from the present band calculation.