Precision spectral densities in correlated systems*

We develop an efficient numerical method to calculate spectral densities of complex impurities based on the Density Matrix Renormalization Group (DMRG) and use it as the impurity solver of the Dynamical Mean Field Theory (DMFT). By using a self-consistent bath configuration with very low entanglement, we take full advantage of the DMRG to calculate dynamical response functions paving the way to treat large effective impurities such as those corresponding to multi-orbital interacting models and multi-site or multi-momenta clusters. It also solves for complex impurities using ab-initio input which opens its realm of applications to real materials. This method leads to reliable calculations of non-local self energies on the real frequency axis directly, at zero temperature. arbitrary dopings and interactions and at all energy scales.
We will show results for multi-site and multi-orbital models in which interesting features arise such as emergent low-energy bound states.