Ab initio procedure for constructing effective models of correlated materials with entangled band structure

Takashi Miyake, Ferdi Aryasetiawan, Masatoshi Imada

Research output: Contribution to journalArticle

105 Citations (Scopus)

Abstract

In a previous work, a procedure for constructing low-energy models of electrons in solids was proposed. 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 thus derived model contains the strength of electron correlation expressed by a partially screened Coulomb interaction, calculated in the constrained random-phase approximation (cRPA), where screening channels within the d space, Pd, are subtracted. One conceptual problem of this established downfolding method is that for entangled bands it is not clear how to cut out the d space and how to distinguish Pd from the total polarization. Here, we propose a simple procedure to overcome this difficulty. The d space is defined to be an isolated set of bands generated from a set of maximally localized Wannier basis, which consequently defines Pd. The r subspace is constructed as the complementary space orthogonal to the d subspace, resulting in two sets of completely disentangled bands. Using these disentangled bands, the effective parameters of the d space are uniquely determined by the cRPA method. The method is successfully applied to 3d transition metals.

Original languageEnglish
Article number155134
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume80
Issue number15
DOIs
Publication statusPublished - 2009 Oct 27
Externally publishedYes

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ASJC Scopus subject areas

  • Condensed Matter Physics
  • Electronic, Optical and Magnetic Materials

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