Regensburg 2022 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 16: Correlated Electrons: Method Development

TT 16.3: Vortrag

Mittwoch, 7. September 2022, 10:15–10:30, H10

Consistency of potential energy in the diagrammatic vertex approximation — •Julian Stobbe and Georg Rohringer — Institute of Theoretical Physic, University of Hamburg, 20355 Hamburg, Germany

In the last decades, dynamical mean field theory (DMFT) and its diagrammatic extensions have been successfully applied to describe local and nonlocal correlation effects in correlated electron systems. Unfortunately, both of them suffer from intrinsic inconsistencies which lead to a violation of the Pauli principle (and related sum rules) as well as the conservation laws of the system. This limits the predictive power of these approaches as fundamental observables such as the kinetic and/or potential energies are not unambiguously defined. Here, we will discuss an approach to overcome the ambiguity in the calculation of the potential energy within the ladder dynamical vertex approximation (DΓA) by introducing an effective mass renormalization parameter in both the charge and the spin susceptibility of the system. The applicability of the method is then demonstrated on the half filled single-band Hubbard model on a three-dimensional cubic lattice. Furthermore, the solution method will be discussed, since the new method requires careful consideration of finite approximation of infinite Matsubara sums.