Berlin 2012 – scientific programme

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O: Fachverband Oberflächenphysik

O 84: Focussed session: Frontiers of electronic structure theory: Strong correlations from first principles VI (jointly with TT)

O 84.1: Topical Talk

Friday, March 30, 2012, 10:30–11:00, HE 101

Dynamically screened Coulomb interaction and GW self-energy in transition metal compounds — •Takashi Miyake — AIST, Tsukuba, Japan

We present a procedure for constructing low-energy models from first-principles using the GW-RPA and Wannier function technique. The procedure starts with dividing the Hilbert space into two subspaces: the low-energy part (d space) and the rest of the space (r space). The low-energy model is constructed for the d space by eliminating the degrees of freedom of the r space. The effective electron interaction of the model is expressed by a partially screened Coulomb interaction which is calculated in the constrained random-phase-approximation (cRPA), where screening channels within the d space are subtracted. As an illustration, the procedure is applied to 3d transition metals, 3d perovskite oxides, and iron-based superconductors. It is found that strength of electron correlation is strongly material dependent. Self-energy effects in quasiparticle bandstructure are analyzed using the GW approximation, which is the lowest-order expansion in the screened Coulomb interaction. Effects of dynamic screening and non-local self-energy (in the Wannier basis) are discussed.