4 research outputs found
Dynamical coherent-potential approximation approach to excitation spectra in 3d transition metals
First-principles dynamical CPA (Coherent-Potential Approximation) for
electron correlations has been developed further by taking into account
higher-order dynamical corrections with use of the asymptotic approximation.
The theory is applied to the investigations of a systematic change of
excitation spectra in transition metals from Sc to Cu at finite
temperatures. It is shown that the dynamical effects damp main peaks in the
densities of states (DOS) obtained by the local density approximation to the
density functional theory, reduce the band broadening due to thermal spin
fluctuations, create the Mott-Hubbard type bands in the case of fcc Mn and fcc
Fe, and create a small hump corresponding to the `6 eV' satellite in the case
of Co, Ni, and Cu. Calculated DOS explain the X-ray photoelectron spectroscopy
data as well as the bremsstrahlung isochromat spectroscopy data. Moreover, it
is found that screening effects on the exchange energy parameters are
significant for understanding the spectra in magnetic transition metals.Comment: To be published in Phys. Rev.