Exploration of coupled cluster Green's function in self-energy embedding theory

We have explored previously developed Coupled Cluster Green’s Function (CCGF) (Shee, Zgid JCTC2019) in two different contexts :

a) As a weak correlation method in a QM-QM embedding method, Self Energy embedding Theory (SEET). This has been envisaged to be useful for the complicated open-shell cases. We have shown difficulties in adapting a non GF based method as a weak correlation method.
b) We have tried successfully CCGF as a solver for SEET before. Now it has been further explored to show that if smaller impurities are used the accuracy of it is almost equivalent to Exact Diagonalization (ED) solver, thus smaller impurities will be preferred over the larger ones. Moreover, we can even reach higher accuracy in comparison to the cases where CCSD has been applied for the entire system.