Activity: Talk or presentation › Talk at conference or symposium › Science to science
In systems containing heavy atoms with open d-shells, both electronic correlations and spin-orbit coupling (SOC) play an important role. Therefore, both have to be included in a successful theory of such materials. A very successful way to account for the electron-electron interaction in crystals is the DFT+DMFT. In this contribution, we explain a strategy to tackle all the obstacles one faces when including SOC in this well-established framework.
Typically, orbitals that can otherwise be treated independently start to hybridize when turning on SOC. This gives rise to Green's functions with important complex-valued off-diagonal elements, which causes difficulties for the impurity solver. In the Monte Carlo solvers that are usually used, a fermionic sign problem appears. We show that a carfully chosen basis rotation can drastically improve this issue. But still, the numerical effort increases significantly when accounting for SOC, as the number of internal symmetries is reduced. We present our approach to reduce the degrees of freedom to make prohibitively costly calculations feasible. All these points are illustrated with a layered oxide heterostructure system as example. Finally we discuss analytic continuation to the real-frequency axis for Green's functions and self-energies with (possibly complex) off-diagonal elements.