Full orbital calculation scheme for materials with strongly correlated electrons

Abstract

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.