Regensburg 2010 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 78: Symposium Density functional theory and beyond for real materials

O 78.1: Hauptvortrag

Donnerstag, 25. März 2010, 14:45–15:15, H1

Downfolded Self-Energy of Many-Electron Systems and the Hubbard U — •Ferdi Aryasetiawan — Graduate School of Advanced Integration Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba-shi, Chiba, 263-8522 Japan

Correlated materials are usually characterised by a partially filled narrow 3d or 4f bands crossing the Fermi level. These materials, such as the 3d perovskites, are hosts to many intriguing properties which cannot be satisfactorily explained within the local density approximation (LDA) or its extensions. The usual approach for treating these systems is to adopt a model Hamiltonian that contains input parameters, notably the Hubbard U, which is often treated as an adjustable parameter. It is therefore highly desirable to construct reliable model Hamiltonians, where the input parameters are computed from first-principles, thus avoiding adjustable parameters which may lead to misleading results.

Here we propose a constrained random-phase approximation (cRPA) scheme [1,2] that allows for a systematic downfolding of high energy screening channels resulting in a low-energy model with a screened Coulomb interaction or the Hubbard U [3]. The model Hamiltonian can then be solved by a number of approaches such as the LDA+U method, the dynamical mean-field theory (DMFT) scheme or the recently introduced LDA+Gutzwiller approach.

[1] Phys. Rev. B 70, 195104 (2004) [2] Phys. Rev. B 80, 155134 (2009) [3] Phys. Rev. Lett. 102, 176402 (2009)