Precision spectral densities in correlated systems

Experiments such as angular resolved photoemission (ARPES), inverse photo-emission (IPE), tunneling or optical conductivity measurements, among others, provide a fundamental source of information to help us understand the microscopic physical processes in materials with strongly correlated electrons.

There has been important progress on the experimental side. However, in spite of promising improvements on the theoretical handling of correlated materials, it is still difficult to obtain precise and detailed theoretical electronic structure results to compare with experiments. In this talk I will review the situation and present recent theoretical approaches based on the use of the Density Matrix Renormalization to calculate spectra for low dimensional systems and as an impurity solver of the Dynamical Mean Field Theory. These techniques pave the way to obtain much more detailed electronic structure results in paradigmatic models for these strongly interacting systems and already present features which had not been observed before using more approximate methods.

We hope that the results presented here, together with the possibility of calculating more precise spectral functions for models of correlated materials, will stimulate a closer study of the details of experimental results and, hence, will contribute to unveil the complex and elusive microscopic behavior of strongly correlated materials.