title: Gutzwiller density functional studies of FeAs-based superconductors: structure optimization and evidence for a three-dimensional Fermi surface.
abstract: The electronic structures of FeAs compounds are sensitive to FeAs bonding, which is described unsuccessfully by the local density approximation (LDA). Treating the multiorbital fluctuations from ab inito LDA+Gutzwiller method, we can now predict the correct FeAs bond length and bonding strength, which will explain the observed "soft phonon." The bands are narrowed by a factor of 2 from their LDA widths. The d{3z{2}-r{2}} orbital is pushed up to cross the Fermi level, forming a three-dimensional Fermi surface, which reduces the anisotropy. The interorbital Hund's coupling J rather than U plays a crucial role in obtaining these results.
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Guangtao
authors.initials: G
authors.lastname: Wang
authors.forename: Yumin
authors.initials: Y
authors.lastname: Qian
authors.forename: Gang
authors.initials: G
authors.lastname: Xu
authors.forename: Xi
authors.initials: X
authors.lastname: Dai
authors.forename: Zhong
authors.initials: Z
authors.lastname: Fang