[Zurück]

A. Valli, T. Schäfer, P. Thunström, G. Rohringer, S. Andergassen, G. Sangiovanni, K. Held, A. Toschi:
"Dynamical vertex approximation in its parquet implementation: Application to Hubbard nanorings";
Physical Review B, 91 (2015), S. 115115-1 - 115115-13.

We have implemented the dynamical vertex approximation (DΓA) in its full parquet-based version to include spatial correlations on all length scales and in all scattering channels. The algorithm is applied to study the electronic self-energies and the spectral properties of finite-size one-dimensional Hubbard models with periodic boundary conditions (nanoscopic Hubbard rings). From a methodological point of view, our calculations and their comparison to the results obtained within dynamical mean-field theory, plain parquet approximation, and the exact numerical solution allow us to evaluate the performance of the DΓA algorithm in the most challenging situation of low dimensions. From a physical perspective, our results unveil how nonlocal correlations affect the spectral properties of nanoscopic systems of various sizes in different regimes of interaction strength.

http://dx.doi.org/10.1103/PhysRevB.91.115115