In this paper, we proposed ab initio calculation of hopping parameters for La2CuO4. The Wannier-function projection procedure of obtaining a small Hamiltonian in real space for different sets of bands of interest was used. The importance of taking into account Cu \(d_{3z^2 - r^2 } \) and apical Oa p z orbitals is shown. The parameters obtained are used to calculate the band structure of undoped La2CuO4 in the framework of the multiband p-d model in the regime of strong electron correlations.

LDA+DMFT, the merger of density functional theory in the local density approximation and dynamical mean-field theory, has been mostly employed to calculate k-integrated spectra accessible by photoemission spectroscopy. In this paper, we calculate k-resolved spectral functions by LDA+DMFT. To this end, we employ the Nth order muffin-tin (NMTO) downfolding to set up an effective low-energy Hamiltonian with three t_2g orbitals. This downfolded Hamiltonian is solved by DMFT yielding k-dependent spectra. Our results show renormalized quasiparticle bands over a broad energy range from -0.7 eV to +0.9 eV with small ``kinks'', discernible in the dispersion below the Fermi energy.

We present parameter-free $\mathrm{LDA}+\mathrm{DMFT}$ (local density $\text{approximation}+\text{dynamical}$ mean field theory) results for the many-body spectra of cubic $\mathrm{Sr}\mathrm{V}{\mathrm{O}}_{3}$ and orthorhombic $\mathrm{Ca}\mathrm{V}{\mathrm{O}}_{3}$. Both systems are found to be strongly correlated metals, but not on the verge of a metal-insulator transition. In spite of the considerably smaller $\mathrm{V}\mathrm{O}\mathrm{V}$ bonding angle in $\mathrm{Ca}\mathrm{V}{\mathrm{O}}_{3}$, the $\mathrm{LDA}+\mathrm{DMFT}$ photoemission spectra of the two systems are very similar, their quasiparticle parts being almost identical. The calculated x-ray absorption spectra show more pronounced, albeit still small, differences. This is in contrast to earlier theoretical and experimental conclusions, but in agreement with recent bulk-sensitive photoemission and x-ray absorption experiments.

We propose a computational scheme for the ab initio calculation of Wannier functions (WFs) for correlated electronic materials. The full-orbital Hamiltonian $\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{H}$ is projected into the WF subspace defined by the physically most relevant partially filled bands. The Hamiltonian ${\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{H}}^{WF}$ obtained in this way, with interaction parameters calculated by constrained local-density approximation (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 matrix self-energy $\mathrm{\ensuremath{\sum}}^{\ifmmode \hat{}\else \^{}\fi{}}(\ensuremath{\epsilon})$ 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 $G(\mathbf{r},{\mathbf{r}}^{\ensuremath{'}},\ensuremath{\epsilon})$. Using $G(\mathbf{r},{\mathbf{r}}^{\ensuremath{'}},\ensuremath{\epsilon})$ one can evaluate the charge density, modified by correlations, together with a new set of WFs, thus defining a fully self-consistent 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 $\mathrm{Sr}\mathrm{V}{\mathrm{O}}_{3}$ and ${\mathrm{V}}_{2}{\mathrm{O}}_{3}$. Comparisons are made with previous results obtained by the LDA+DMFT approach where the LDA density of states was used as input, and with new bulk-sensitive experimental spectra.

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.

Optical spectra of a quasi-two-dimensional Ca2-xSxRuO4 system have been studied. Strong changes have been revealed upon the transition from the composition with x = 0, at which the material is an antiferromagnetic insulator, to compositions with x > 0.2, where the system transforms into the state of a paramagnetic metal. Calculations of the electronic structure of these materials have been performed. The main peaks in the experimental curves were found to have corresponding features in the calculated theoretical spectra.

We present parameter-free LDA+DMFT results for the many-particle density of states of cubic SrVO3 and orthorhombic CaVO3. Both systems are found to be strongly correlated metals, but em not on the verge of a metal-insulator transition. In spite of the considerably smaller V-O-V bonding angle in CaVO3 the photoemission spectra of the two systems are very similar, their quasiparticle parts being almost identical. This is in contrast to earlier theoretical and experimental conclusions, but in agreement with recent bulk-sensitive photoemission experiments.

The electronic structures of the metallic and insulating phases of the alloy series Ca2-xSrxRuO4 (0 ≤x ≤ 2) are calculated using LDA, LDA+U and Dynamical Mean-Field Approximation methods. In the end members the groundstate respectively is an orbitally non-degenerate antiferromagnetic insulator (x = 0) and a good metal (x = 2). For x > 0.5 the observed Curie-Weiss paramagnetic metallic state which possesses a local moment with the unexpected spin S = 1/2, is explained by the coexistence of localized and itinerant Ru-4d-orbitals. For 0.2 < x < 0.5 we propose a state with partial orbital and spin ordering. An effective model for the localized orbital and spin degrees of freedom is discussed. The metal-insulator transition at x = 0.2 is attributed to a switch in the orbital occupation associated with a structural change of the crystal.

The electronic structures of the metallic and insulating phases of the alloy series Ca(2-x)Sr(x)RuO4 (0 <= x <= 2) are calculated using LDA, LDA+U and Dynamical Mean-Field Approximation methods. In the end members the groundstate respectively is an orbitally non-degenerate antiferromagnetic insulator (x=0) and a good metal (x=2). For x>0.5 the observed Curie-Weiss paramagnetic metallic state which possesses a local moment with the unexpected spin S=1/2, is explained by the coexistence of localized and itinerant Ru-4d-orbitals. For 0.2

The electronic structures of the metallic and insulating phases of Ca(2-x)Sr(x)RuO(4) (0<= x <= 2) are calculated using LDA, LDA+U and Dynamical Mean-Field Approximation methods. For x=0 the ground state is an orbitally non-degenerate antiferromagnetic insulator. For 0.20.5 the observed Curie-Weiss paramagnetic metallic state possessing a local moment with the unexpected spin S=1/2 is explained by the localization of only two of the three Ru-4d-orbitals.

the date of receipt and acceptance should be inserted later Abstract. The electronic structures of the metallic and insulating phases of the alloy series Ca2−xSrxRuO4 (0 ≤ x ≤ 2) are calculated using LDA, LDA+U and Dynamical Mean-Field Approximation methods. In the end members the groundstate respectively is an orbitally non-degenerate antiferromagnetic insulator (x = 0) and a good metal (x = 2). For x > 0.5 the observed Curie-Weiss paramagnetic metallic state which possesses a local moment with the unexpected spin S = 1/2, is explained by the coexistence of localized and itinerant Ru-4d-orbitals. For 0.2 < x < 0.5 we propose a state with partial orbital and spin ordering. An effective model for the localized orbital and spin degrees of freedom is discussed. The metal-insulator transition at x = 0.2 is attributed to a switch in the orbital occupation associated with a structural change of the crystal.