LDA++ approach to the electronic structure of magnets: correlation effectsin iron

A novel approach to the investigation of correlation effects in the electro nic structure of magnetic crystals which takes into account a frequency dep endence of the self-energy (the so-called 'LDA++ approach') is developed. T he fluctuation-exchange approximation is generalized to the spin-polarized multi-band case and a local version of it is proposed. As an example, we ca lculate the electronic quasiparticle spectrum of ferromagnetic iron. It is shown that the Fermi-liquid description of the bands near the Fermi level i s reasonable, while the quasiparticle states beyond approximately the 1 eV range are strongly damped, in agreement with photoemission data. The result of the spin-polarized thermoemission experiment is explained satisfactoril y. The problem of satellite structure is discussed.