Application of Many-Body Perturbation Theory to the Description of Correlated Metals

An efficient computational LSDA+DMFT toolbox for the description of
correlated materials has been established. The method developed in
this work provides an appropriate description of 3d-transition
metal correlated bulk systems, concerning their ground-state
properties (magnetic moments, total energies) as well as the high-
and low-energy spectroscopies (valence-band angular-resolved
photoemission, Fano-effect, optical and magneto-optical
properties). The incorporation of the perturbational impurity
solvers within the spin-polarized relativistic
Korringa-Kohn-Rostoker (SPR-KKR) Green’s function method gives rise
to a fully self-consistent procedure with respect both to the DFT
(charge) and the DMFT (localized dynamical self-energy)
self-consistency requirements. Thus, the solution of the
many-electron problem can be achieved with a high precision. In
turn this opens a possibility to investigate very delicate
properties, as the orbital magnetic moments of 3d-transition
metals. To develop a relatively fast and accurate approach for the
low-energy spectroscopies, the DMFT was implemented within the wave
function formalism in the framework of the Linearized Muffin-Tin
Orbitals method (LMTO). Calculations are performed in a one-shot
run, that does not allow to get the charge-self-consistent
solution. In such a way all effects of the localized correlations
are encapsulated in the Green’s function constructed as a resolvent
to the LMTO one-particle Hamiltonian and accounting for the
corresponding self-energy via the Dyson equation. The LMTO+DMFT
scheme gives in comparison to a plain LSDA a significantly improved
description of the magneto-optics in the 3d-transition metals,
half-metallic Heusler ferromagnet NiMnSb, as well as for the
heavy-fermion US compound.