9 research outputs found
Non-quasiparticle states in the core level spectra of ferromagnetic semiconductors and half-metallic ferromagnets
The Green's functions that determine x-ray spectra are calculated in the s-d
exchange model of a saturated conducting ferromagnet in the presence of the
core hole. A possibility to observe non-quasiparticle (NQP) states in the core
level (x-ray absorption, emission and photoelectron) spectroscopy is
demonstrated. It is shown that NQP contributions to resonant x-ray scattering
spectra can be considerably enhanced by core hole effects in comparison with
those to the density of states.Comment: 13 pages, 7 figures, final versio
Ground-state phase diagrams of the generalized Falicov-Kimball model with Hund coupling
Charge and spin orderings are studied on the simplest 1D and the 2D square
lattice within the generalized Falicov-Kimball model with Hund coupling between
localized and itinerant electrons. Using the restricted phase diagrams method
(RPDM) a number of simple rules of formation of various sorts of ground state
phases have been detected. In particular, relationships between density of
current carriers (electrons or holes) and type of charge and magnetic
arrangement has been determined. In 2D in the mixed valence regime only axial
stripes (vertical or horizontal) have been found for intermediate values of the
coupling constants. They are composed of ferromagnetic or antiferromagnetic
chains interchanged with non-magnetic ones. For band fillings close to the half
filling stripe phases oriented along one of the main diagonal direction are
formed. The results suggest a possibility of tuning modulations of charge and
magnetic superstructures with a change of doping.Comment: 10 pages, 6 figures; Fig. 2 slightly modified and the text adjusted
accordingly, references adde
Examination of several density functionals in numerical Kohn-Sham calculations for atoms
Andrae D, Brodbeck R, Hinze J. Examination of several density functionals in numerical Kohn-Sham calculations for atoms. INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY. 2001;82(5):227-241.We studied several exchange-only and exchange-correlation energy density functionals in numerical, i.e., basis-set-free, nonrelativistic Kohn-Sham calculations for closed-shell IS states of atoms and atomic ions with N electrons, where 2 less than or equal to N less than or equal to 120. Accurate total energies are presented to serve as reference data for algebraic approaches, as do the numerical Hartree-Fock results, which are also provided. Gradient-corrected exchange-only functionals considerably improve the total energies obtained from the usual local density approximation, when compared to the Hartree-Fock results. Such an improvement due to gradient corrections is not seen in general for highest orbital energies, neither for exchange-only results (to be compared with Hartree-Fock results), nor for exchange-correlation results (to be compared with experimental ionization energies). (C) 2001 John Wiley & Sons, Inc