COULOMB CORRELATION EFFECTS IN LaFeAsO: AN LDA + DMFT( QMC) STUDY
Shorikov A.O., Korotin M.A., Streltsov S.V., Skornyakov S.L., Korotin D.M., Anisimov V.I.

Поступила в редакцию: 10 Июня 2008

PACS: 74.25.Jb, 71.27.+a, 71.30.+h

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Effects of Coulomb correlation on the LaFeAsO electronic structure are investigated by the LDA + DMFT(QMC) method (combination of the local density approximation with the dynamic mean-field theory; impurity solver is a quantum Monte Carlo algorithm). The calculation results show that LaFeAsO is in the regime of intermediate correlation strength with a significant part of the spectral density moved from the Fermi energy to the Hubbard bands and far from the edge of the metal-insulator transition. Correlations affect iron d-orbitals differently. The t_2g states (xz, yz and x²-y² orbitals) have a higher energy due to crystal field splitting and are nearly half-filled. Their spectral functions have a pseudogap with the Fermi level position on the higher subband slope. The lower energy e_g set (xy and 3z²-r² orbitals) have occupancies significantly larger than with typically metallic spectral functions.