Speaker
Description
I will illustrate possible applications of the "mixed-configuration approximation" (MCA) [1,2], an approximate method that combines the solutions to independent impurity problems obtained with single-band impurity solvers to study nonequilibrium multiorbital systems at moderate computational cost. We merge the MCA with the so-called auxiliary master equation approach (AMEA) single-impurity solver. As a benchmark, I will first show that our approach reproduces the results of quantum Monte Carlo (QMC) for two-orbital impurity models at equilibrium with overall good accuracy, especially for nondegenerate orbitals. I will then use MCA+AMEA as an impurity solver for dynamical mean-field theory (DMFT) to address the case of a two-orbital, realistic layered structure, recovering the strong crystal-field-driven charge polarization observed by solving the DMFT self-consistent cycle with QMC, albeit slightly reduced. Finally, I will address a prototype nonequilibrium setup by sandwiching this layer between metallic contacts subject to a bias voltage described by different chemical potentials. This simplified model demonstrates our method's potential to access nonequilibrium steady-state behavior of multiorbital, realistic materials. These findings provide a first-step basis for theoretical studies of nonequilibrium properties of multiorbital compounds directly in the real frequency domain.
[1] Mazzocchi et al., Phys. Rev. B 112, 155127 (2025)
[2] Mazzocchi et al., arXiv:2602.05664