Qiu, YihengHenderson, Thomas M.Zhao, JinmoScuseria, Gustavo E.2018-11-192018-11-192018Qiu, Yiheng, Henderson, Thomas M., Zhao, Jinmo, et al.. "Projected coupled cluster theory: Optimization of cluster amplitudes in the presence of symmetry projection." <i>The Journal of Chemical Physics,</i> 149, no. 16 (2018) AIP Publishing: https://doi.org/10.1063/1.5053605.https://hdl.handle.net/1911/103360Methods which aim at universal applicability must be able to describe both weak and strong electronic correlation with equal facility. Such methods are in short supply. The combination of symmetry projection for strong correlation and coupled cluster theory for weak correlation offers tantalizing promise to account for both on an equal footing. In order to do so, however, the coupled cluster portion of the wave function must be optimized in the presence of the symmetry projection. This paper discusses how this may be accomplished, and shows the importance of doing so for both the Hubbard model Hamiltonian and the molecular Hamiltonian, all with a computational scaling comparable to that of traditional coupled cluster theory.engArticle is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.Journal articlehttps://doi.org/10.1063/1.5053605