8 research outputs found
Electronic Structure Calculations of Magnetic Exchange Interactions in Europium Monochalcogenides
Using a combination of local spin density and Hubbard 1 approximations we
study the mechansim of exchange interacion in EuX (X=O, S, Se and Te). We
reproduce known experimental results about bulk modulus, critical pressure for
structural phase transition, magnetic ordering temperature, spin--wave
dispersions as well as momentum-- and tempearuture--dependent band shift. Our
numerical results show pressure induced competition between the hybirization
enhanced exchange interaction and Kondo--like coupling in EuO. Possible ways to
enhance T_{c} are discussed
Calculations of Magnetic Exchange Interactions in Mott--Hubbard Systems
An efficient method to compute magnetic exchange interactions in systems with
strong correlations is introduced. It is based on a magnetic force theorem
which evaluates linear response due to rotations of magnetic moments and uses a
novel spectral density functional framework combining our exact diagonalization
based dynamical mean field and local density functional theories. Applications
to spin waves and magnetic transition temperatures of 3d metal mono--oxides as
well as high--T_{c} superconductors are in good agreement with experiment
Many-Body Electronic Structure of Americium metal
We report computer based simulations of energetics, spectroscopy and
electron-phonon interaction of americium using a novel spectral density
functional method. This approach gives rise to a new concept of a many-body
electronic structure and reveals the unexpected mixed valence regime of Am 5f6
electrons which under pressure acquire the 5f7 valence state. This explains
unique properties of Am and addresses the fundamental issue of how the
localization delocalization edge is approached from the localized side in a
closed shell system.Comment: 4 pages, 3 figure
Cellular Dynamical Mean Field Approach to Strongly Correlated Systems
We propose a cellular version of dynamical-mean field theory which gives a
natural generalization of its original single-site construction and is
formulated in different sets of variables. We show how non-orthogonality of the
tight-binding basis sets enters the problem and prove that the resulting
equations lead to manifestly causal self energies.Comment: RevTex, 4 pages, 1 embedded figur
Importance of Correlation Effects on Magnetic Anisotropy in Fe and Ni
We calculate magnetic anisotropy energy of Fe and Ni by taking into account
the effects of strong electronic correlations, spin-orbit coupling, and
non-collinearity of intra-atomic magnetization. The LDA+U method is used and
its equivalence to dynamical mean-field theory in the static limit is
emphasized. Both experimental magnitude of MAE and direction of magnetization
are predicted correctly near U=4 eV for Ni and U=3.5 eV for Fe. Correlations
modify one-electron spectra which are now in better agreement with experiments.Comment: 4 pages, 2 figure
# by Oldenbourg Wissenschaftsverlag, München Electronic structure and magnetic properties of solids
Computational crystallography Abstract. We review basic computational techniques for simulations of various magnetic properties of solids. Several applications to compute magnetic anisotropy energy, spin wave spectra, magnetic susceptibilities and temperature dependent magnetisations for a number of real systems are presented for illustrative purposes. 1