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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.

PACS 71.15.Mb, 71.27.+ a, 71.30.+ h Conventional band structure calculations in the local density approximation (LDA) [1 -3] are highly successful for many materials, but miss important aspects of the physics and energetics of strongly correlated electron systems, such as transition metal oxides and f-electron systems displaying, e.g., Mott insulating and heavy quasiparticle behavior. In this respect, the LDA + DMFT approach which merges LDA with a modern many-body approach, the dynamical mean-field theory (DMFT), has proved to be a breakthrough for the realistic modeling of correlated materials. Depending on the strength of the electronic correlation, a LDA + DMFT calculation yields the weakly correlated LDA results, a strongly correlated metal, or a Mott insulator. In this paper, the basic ideas and the set-up of the LDA + DMFT(X) approach, where X is the method used to solve the DMFT equations, are discussed. Results obtained with X = QMC (quantum Monte Carlo) and X = NCA (non-crossing approximation) are presented and compared, showing that the method X matters quantitatively. We also discuss LDA + DMFT results for two prime examples of correlated materials, i.e., V 2 O 3 and Ce which undergo a Mott -Hubbard metal -insulator and volume collapse transition, respectively.

We propose a computational scheme for the ab initio calculation of Wannier functions (WFs) for correlated electronic materials. The full-orbital HamiltonianĤ is projected into the WF subspace defined by the physically most relevant partially filled bands. The HamiltonianĤ W F obtained in this way, with interaction parameters calculated by constrained LDA for the Wannier orbitals, is used as an ab initio setup of the correlation problem, which can then be solved by many-body techniques, e.g., dynamical mean-field theory (DMFT). In such calculations the self-energy operator Σ(ε) is defined in WF basis which then can be converted back into the full-orbital Hilbert space to compute the full-orbital interacting Green function G(r, r ′ , ε). Using G(r, r ′ , ε) one can evaluate the charge density, modified by correlations, together with a new set of WFs, thus defining a fully selfconsistent scheme. The Green function can also be used for the calculation of spectral, magnetic and electronic properties of the system. Here we report the results obtained with this method for SrVO 3 and V 2 O 3 . Comparisons are made with previous results obtained by the LDA+DMFT approach where the LDA DOS was used as input, and with new bulk-sensitive experimental spectra.