We aim at developing and implementing new, unbiased approaches to many electron systems by combining cluster embedding approaches and diagrammatic Monte Carlo techniques.
The Cluster Embeddings Group will first work on understanding the analytic and convergence properties of Feynman diagrammatic perturbation series. While these techniques have been known for several decades, only recent progress allows the series to be computed quantitatively with diagrammatic Monte Carlo codes. The group will focus on finding strategies to control the convergence of these series. This will open the way for the elaboration of new cluster embedding schemes where classes of diagrams are summed with the help of continuous-time quantum Monte Carlo algorithms. The group will implement and establish the efficiency and applicability range of these schemes on the Hubbard model. The results can then be generalized to other systems with impact for several projects of the Simons Collaboration on the Many Electron Problem.