Effect of spin orbit coupling and Hubbard $U$ on the electronic structure of IrO${}_2$

We have studied in detail the electronic structure of IrO${}_2$ including spin-orbit coupling (SOC) and electron-electron interaction, both within the GGA+U and GGA+DMFT approximations. Our calculations reveal that the Ir t${}_{2g}$ states at the Fermi level largely retain the J${}_{\mathrm{e}\mathrm{f}\mathrm{f}}$ = $\frac{1}{2}$ character, suggesting that this complex spin-orbit entangled state may be robust even in metallic IrO${}_2$. We have calculated the phase diagram for the ground state of IrO${}_2$ as a function of $U$ and find a metal insulator transition that coincides with a magnetic phase change, where the effect of SOC is only to reduce the critical values of $U$ necessary for the transition. We also find that dynamic correlations, as given by the GGA+DMFT calculations, tend to suppress the spin-splitting, yielding a Pauli paramagnetic metal for moderate values of the Hubbard $U$. Our calculated optical spectra and photoemission spectra including SOC are in good agreement with experiment demonstrating the importance of SOC in IrO${}_2$.