We report high-resolution high-energy photoemission spectra together with parameter-free LDA + DMFT (local density approximation + dynamical mean-field theory) results for Sr1-xCaxVO3, a prototype 3d(1) system. In contrast to earlier investigations the bulk spectra are found to be insensitive to x. The good agreement between experiment and theory confirms the bulk sensitivity of the high-energy photoemission spectra.

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In rare earth compounds, the crystal electric fields (CEF) on the 4f electrons determine various physical properties, i.e., magnetic, optical, thermal and electrical properties. 1) The 4f electrons on a rare earth ion experience an electrostatic crystal field potential which is set up by the surrounding charge distribution. Thus, the potential reflects the local point symmetry of the site of the rare earth ion. For about two decades, it has been believed that the same formula of CEF is applicable for all the cubic point groups, T (23), T h (m3), O (432), T d (43m) and O h (m3m). 2, 3) Recently, we have investigated the CEF for T and T h by the group theory and a simple point charge model and found that the above belief is incorrect, because T and T h do not contain the two types of symmetry operations of O: C 4 (rotations through π/2 about the fourfold symmetry axis) and C 2 (Umklappung, rotations through π perpendicular to the principle rotation axis). 4) In this letter, we derive the correct formula of CEF for T and T h . The inelastic neutron scattering technique has the attractive feature that it probes both the eigenvalues through the transition energies and the eigenfunctions through the transition intensities. 5) Thus, to confirm our formula by neutron scattering experiments, we investigate the transition intensities and selection rules for T and T h as well.Hereafter, we consider the 4f electron systems. On the basis of the simple point charge model, 6) as shown in the previous paper, 7) the CEF potential is written asCrystal electric fields for the cubic point groups are reexamined and it is found that the new term O 2 6 −O 6 6 is nonvanishing for the cubic point groups T h and T due to the lack of Umklappung and fourfold symmetry axis of the point group O h . The eigenfunctions and eigenvalues of the crystal electric field for 4f n configurations are labeled by the irreducible representations of the point group T h . The degeneracy of each sublevel does not change as compared with those of the point group O h , but some eigenfunctions and eigenvalues are affected by the new term. Thus inelastic neutron scattering spectra for T and T h are different from those for O h due to different transition probabilities and selection rules.KEYWORDS: crystal electric fields, cubic point groups, 4f electrons, rare earth compounds, inelastic neutron scattering spectrawhere q i is the charge of the ith neighboring ion at a distance R i from the origin and Y kq (Ω) is a normalized spherical harmonic. 8) For the 4f n configurations, the matrix elements of C kq can be calculated using the tensor operator methods 8) and the matrix elements for the Russell-Saunders coupling (LS coupling) scheme are shown in the previous paper. 7)In the Stevens' operator equivalent methods, the CEF potential is written aswhere O q k (c) are the most commonly used operator equivalents O q k and O q k (s) are the sine-term operator equivalents. 6, 7) The relationships between the coefficients B kq and A kq (p) are shown in the previous paper...

Some filled skutterudite compounds have recently been found to exhibit very interesting properties: a metal-insulator transition (PrRu 4 P 12 ), an antiferroquadrupole ordering and heavy-fermion behaviour under magnetic fields (PrFe 4 P 12 ) and a new class of heavy-fermion superconductivity (PrOs 4 Sb 12 ). Such varied and interesting physical properties are thought to reflect the Fermi surface properties. Band structure calculations have revealed the characteristics of the conduction bands. The main conduction band consisting of p orbitals of pnictogen surrounding the rare-earth ions has a nesting property, and strongly hybridizes with one of 4f electrons. One of the other conduction bands does not have mixing matrix elements with 4f electrons, resulting in the unique band structure in CeOs 4 Sb 12 .

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