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Register a new userSelf-interaction Corrected Calculations of Correlated f-electron Systems
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The electronic structures of several actinide solid systems are calculated using the self-interaction corrected local spin density approximation. Within this scheme the $5f$ electron manifold is considered to consist of both localized and delocalized states, and by varying their relative proportions the energetically most favourable (groundstate) configuration can be established. Specifically, we discuss elemental Pu in its $delta$-phase, PuO$_2$ and the effects of addition of oxygen, the series of actinide monopnictides and monochalcogenides, and the UX$_3$, X= Rh, Pd, Pt, Au, intermetallic series.
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We present a novel approach to calculate the effective exchange interaction parameters based on the realistic electronic structure of correlated magnetic crystals in local approach with the frequency dependent self energy. The analog of ``local force theorem in the density functional theory is proven for highly correlated systems. The expressions for effective exchange parameters, Dzialoshinskii- Moriya interaction, and magnetic anisotropy are derived. The first-principle calculations of magnetic excitation spectrum for ferromagnetic iron, with the local correlation effects from the numerically exact QMC-scheme is presented.
Quantum fluctuations and related phase transitions are of current interest from the viewpoint of fundamental physics and technological applications. Quantum phase implies a region where the quantum fluctuations of energy scale $hbaromega$ dominates over the thermal energy $k_B$T. Presence of quantum phase leads to unconventional and unexpected physical phenomena like Kondo effect, non-Fermi liquids, ordered magnetic state, and Fermi liquids, etc. In this framework, Ce-based metallic compounds, exhibiting correlated electron phenomena, emerged as prototypical systems to study the various quantum phases. In these systems considerable efforts have been made, both experimentally and theoretically, to overcome the problems related to the comprehensive understanding of correlated quantum phases. In this article, various aspects related to quantum phases in CeNiGe2, CeGe and CeAlGe are summarized, mainly focusing on the structural and physical properties.
We introduce a new linear response method to study the lattice dynamics of materials with strong correlations. It is based on a combination of dynamical mean field theory of strongly correlated electrons and the local density functional theory of electronic structure of solids. We apply the method to study the phonon dispersions of a prototype Mott insulator NiO. Our results show overall much better agreement with experiment than the corresponding local density predictions.
A first-principles theory of resonant magnetic scattering of x rays is presented. The scattering amplitudes are calculated using a standard time-dependent perturbation theory to second order in the electron-photon interaction vertex. In order to calculate the cross section reliably an accurate description of the electronic states in the material under investigation is required and this is provided by the density functional theory (DFT) employing the Local Spin Density Approximation combined with the self-interaction corrections (SIC-LSD). The magnetic x-ray resonant scattering (MXRS) theory has been implemented in the framework of the relativistic spin-polarized LMTO-ASA band structure calculation method. The theory is illustrated with an application to ferromagnetic praseodymium. It is shown that the theory quantitatively reproduces the dependence on the spin and orbital magnetic moments originally predicted qualitatively (Blume, J. Appl. Phys, {bf 57}, 3615 (1985)) and yields results that can be compared directly with experiment.
Combining the density functional theory (DFT) and the Gutzwiller variational approach, a LDA+Gutzwiller method is developed to treat the correlated electron systems from {it ab-initio}. All variational parameters are self-consistently determined from total energy minimization. The method is computationally cheaper, yet the quasi-particle spectrum is well described through kinetic energy renormalization. It can be applied equally to the systems from weakly correlated metals to strongly correlated insulators. The calculated results for SrVO$_3$, Fe, Ni and NiO, show dramatic improvement over LDA and LDA+U.
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