Dynamical mean-field approach to materials with strong electronic correlations

Abstract

We review recent results on the properties of materials with correlated electrons obtained within the LDA+DMFT approach, a combination of a conventional band structure approach based on the local density approximation (LDA) and the dynamical mean-field theory (DMFT). The application to four outstanding problems in this field is discussed: (i) we compute the full valence band structure of the charge-transfer insulator NiO by explicitly including the p-d hybridization, (ii) we explain the origin for the simultaneously occuring metalinsulator transition and collapse of the magnetic moment in MnO and Fe2O3, (iii) we describe a novel GGA+DMFT scheme in terms of plane-wave pseudopotentials which allows us to compute the orbital order and cooperative Jahn-Teller distortion in KCuF3 and LaMnO3, and (iv) we provide a general explanation for the appearance of kinks in the effective dispersion of correlated electrons in systems with a pronounced three-peak spectral function without having to resort to the coupling of electrons to bosonic excitations. These results provide a considerable progress in the fully microscopic investigations of correlated electron materials.

Prediction of variation in d-orbital occupancy in strain induced tetragonal phase of BiFeO3 thin film

“…68 A lot of research work has been performed on this issue. [69][70][71][72][73] Also, there have been reports where calculations performed using the AMF functional showed the spin crossover from low to high spin states with the variation of parameter U. 66,67 Hence in order to get a complete insight about the electronic and magnetic properties of BFO in tetragonal (P4mm) phase, a series of calculations using the AMF and FLL functionals were performed by varying U from 2.72 eV to 10.88 eV while keeping J, constant to values ranging from 0.27 eV to 1.22 eV, as shown in Tables I-V respectively. For all the calculations performed using the AMF and FLL functionals given above in Tables I to V, it was observed that for the combination of parameters U=10.88 eV and J=0.27 eV, performed using the AMF functional gave S=1/2 spin state as given in Table I.…”

Dynamical Mean-Field Theory

“…These materials range from 3d transition metals and their oxides, and f electron systems, all the way to Heusler alloys, ferromagnetic half-metals, fullerenes, and zeolites [52,[95][96][97][98]. Nevertheless, this framework still needs to be considerably improved before it becomes a truly comprehensive ab initio approach for complex correlated matter with predictive power.…”

LDA+DMFT approach to ordering phenomena and the structural stability of correlated materials

“…Within the DFT+DMFT calculation the total energy is then evaluated using the expression [24][25][26]130] …”

“…In particular, this method was used to study the electronic and structural properties of elemental Fe [27,28,134] and the iron chalcogenide FeSe [144], and to explain the cooperative Jahn-Teller effect in paramagnetic KCuF 3 and LaMnO 3 [24][25][26].…”

“…Employing a novel implementation of DFT+DMFT in combination with planewave pseudopotentials it was recently demonstrated that, by performing total-energy calculations for correlated materials, it is possible to compute atomic displacements, perform structural optimizations, determine the lattice dynamics, and explore structural transitions caused by electronic correlations [24][25][26][27][28][29]. Thereby the DFT+DMFT computational scheme is able to treat electronic and structural properties of strongly correlated materials on the same footing.…”