Dynamical mean-field theory within an augmented plane-wave framework: Assessing electronic correlations in the iron pnictide LaFeAsO

• Autores: Aichhorn, Markus; Pourovskii, Leonid; Vildosola, Veronica Laura; Ferrero, Michel; Parcollet, Olivier; Miyake, Takashi; Georges, Antoine; Biermann, Silke
• Año de publicación: 2009
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Density functional theory; Local density approximation, gradient and other corrections; Transition metals and alloys; Superconducting materials
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

We present an approach that combines the local-density approximation (LDA) and the dynamical mean-field theory (DMFT) in the framework of the full-potential linear augmented plane-wave method. Wannier-type functions for the correlated shell are constructed by projecting local orbitals onto a set of Bloch eigenstates located within a certain energy window. The screened Coulomb interaction and Hund’s coupling are calculated from a first-principles constrained random-phase approximation scheme. We apply this LDA+DMFT implementation, in conjunction with a continuous-time quantum Monte Carlo algorithm, to the study of electronic correlations in LaFeAsO. Our findings support the physical picture of a metal with intermediate correlations. The average value of the mass renormalization of the Fe 3⁢ bands is about 1.6, in reasonable agreement with the picture inferred from photoemission experiments. The discrepancies between different LDA+DMFT calculations (all technically correct) which have been reported in the literature are shown to have two causes: (i) the specific value of the interaction parameters used in these calculations and (ii) the degree of localization of the Wannier orbitals chosen to represent the Fe 3⁢ states, to which many-body terms are applied. The latter is a fundamental issue in the application of many-body calculations, such as DMFT, in a realistic setting. We provide strong evidence that the DMFT approximation is more accurate and more straightforward to implement when well-localized orbitals are constructed from a large energy window encompassing Fe-3⁢, As-4⁢, and O-2⁢ and point out several difficulties associated with the use of extended Wannier functions associated with the low-energy iron bands. Some of these issues have important physical consequences regarding, in particular, the sensitivity to the Hund’s coupling.
Fil: Aichhorn, Markus. École Polytechnique; Francia
Fil: Pourovskii, Leonid. École Polytechnique; Francia
Fil: Vildosola, Veronica Laura. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. École Polytechnique; Francia. Comisión Nacional de Energía Atómica. Gerencia de Área Investigaciones y Aplicaciones No Nucleares. Gerencia Física (CAC). Departamento de Física de la Materia Condensada; Argentina. Japan Science and Technology Agency; Japón
Fil: Ferrero, Michel. École Polytechnique; Francia. Institut de Physique Théorique; Francia
Fil: Parcollet, Olivier. Institut de Physique Théorique; Francia
Fil: Miyake, Takashi. Japan Science and Technology Agency; Japón. Research Institute for Computational Science; Japón
Fil: Georges, Antoine. École Polytechnique; Francia. Japan Science and Technology Agency; Japón. Collège de France; Francia
Fil: Biermann, Silke. École Polytechnique; Francia. Japan Science and Technology Agency; Japón