Self-consistent $GW$ determination of the interaction strength: Application to the iron arsenide superconductors

We introduce a first principles approach to determine the strength of the electronic correlations based on the fully self-consistent $GW$ approximation. The approach provides a seamless interface with dynamical mean field theory, and gives good results for well studied correlated materials such as NiO. Applied to the recently discovered iron arsenide materials, it accounts for the noticeable correlation features observed in optics and photoemission while explaining the absence of visible satellites in x-ray absorption experiments and other high energy spectroscopies.

Figure 1

(Color online) (a) and (b) Slater integrals versus Matsubara frequency as computed by fully self-consistent $GW$ method, (c) corresponding Hund’s coupling strength $J$, and (d) the difference between the $GW$ Coulomb interaction and its Slater parameterization.

Figure 2

(Color online) (a) $A\left(\mathbf{k},\omega \right)$ of ${\text{BaFe}}_2{\text{As}}_2$ at $T=150\text{K}$ as computed by $\text{LDA}+\text{DMFT}$. The inset shows the path in momentum space, while the gray inset shows the ARPES intensity from Ref. 9. (b) Optical conductivity of $\text{LDA}+\text{DMFT}$ method (DMFT) and its comparison with experiment of Ref. 4 (exper.). Also shown is the LDA optical conductivity and $\text{LDA}+\text{DMFT}$ conductivity with substantially smaller $F_0$ of Ref. 10 (DMFT-w). The legend contains the strength of the Drude peak, which is broadened only due to electron-electron interactions. (c) Temperature dependence of the optical conductivity within $\text{LDA}+\text{DMFT}$.

Figure 3

(Color online) Total and partial density of states of $\text{LDA}+\text{DMFT}$ method compared to LDA density of states.

Figure 4

(Color online) The atomic histogram of the $\text{Fe-}3d$ shell for ${\text{BaFe}}_2{\text{As}}_2$. The atomic states (all 1024) are sorted according to their valence $N$. Below the arrow we also display the multiplet splitting of the atomic states in each valence. The $N=5$ and $N=6$ valences show the largest splitting of 7 and 6.5 eV, resulting in a very broad lower Hubbard band of the one electron density of states.