A Power Series Approximation in Symmetry Projected Coupled Cluster Theory

Abstract

Projected Hartree-Fock theory provides an accurate description of many kinds of strong correlations but does not properly describe weakly-correlated systems. On the other hand, single-reference methods such as configuration interaction or coupled cluster theory can handle weakly-correlated problems but cannot properly account for strong correlations. Ideally, we would like to combine these approaches in a symmetry-projected coupled cluster approach, but this is far from straightforward. In this work, we provide an alternative formulation to identify the so-called disentangled cluster operators which arise when we combine these two methodological strands. Our formulation shows promising results for model systems and small molecules.

References in corpus (5)

• Quasiparticle Coupled Cluster Theory for Pairing Interactions
• Ab initio Bogoliubov coupled cluster theory for open-shell nuclei
• Symmetry broken and restored coupled-cluster theory I. Rotational symmetry and angular momentum
• Coordinate descent full configuration interaction
• Combining symmetry breaking and restoration with configuration interaction: a highly accurate many-body scheme applied to the pairing Hamiltonian

Cited by in corpus (1)

• Strong-Weak Duality via Jordan-Wigner Transformation: Using Fermionic Methods for Strongly Correlated $su(2)$ Spin Systems