Applicability and limiations of Cluster Perturbation Theory for Hubbard models

These are the Cluster Greensfunctions that were used in the paper "Applicability and limiations of Cluster
Perturbation Theory for Hubbard models" published as part of the special edition “S.I.: Non-Equilibrium Quantum
Physics, Many Body Systems, and Foundations of Quantum Mechanics” in the European Journal of Phyiscs in 2023.
The Greensfunctions were generated via a Chebyshev expansion and are currently in a real space representation.
You may use python and import them via numpy as follows:

```console
import numpy as np

MC = <number_of_sites> # Here you have to add the number of cluster sites (e.g. 16 for a 4x4 cluster)

greensfunctions = np.genfromtxt("<file_name>")
greensfunctions = greensfunctions.reshape(greensfunctions.shape[0], MC, MC)
```

This way you obtain a tensor where the first dimension corresponds to the frequency and the other two
to the real space indices.

For further questions please contact the corresponding author Nicklas Enenkel via E-mail
(nicklas.enenkel@quantumsimulations.de)