Jiménez-Hoyos, Carlos A.Rodríguez-Guzmán, R.Scuseria, Gustavo E.2017-05-042017-05-042013Jiménez-Hoyos, Carlos A., Rodríguez-Guzmán, R. and Scuseria, Gustavo E.. "Multi-component symmetry-projected approach for molecular ground state correlations." <i>The Journal of Chemical Physics,</i> 139, no. 20 (2013) American Institute of Physics: https://doi.org/10.1063/1.4832476.https://hdl.handle.net/1911/94177The symmetry-projected Hartree–Fock ansatz for the electronic structure problem can efficiently account for static correlation in molecules, yet it is often unable to describe dynamic correlation in a balanced manner. Here, we consider a multi-component, systematically improvable approach, that accounts for all ground state correlations. Our approach is based on linear combinations of symmetry-projected configurations built out of a set of non-orthogonal, variationally optimized determinants. The resulting wavefunction preserves the symmetries of the original Hamiltonian even though it is written as a superposition of deformed (broken-symmetry) determinants. We show how short expansions of this kind can provide a very accurate description of the electronic structure of simple chemical systems such as the nitrogen and the water molecules, along the entire dissociation profile. In addition, we apply this multi-component symmetry-projected approach to provide an accurate interconversion profile among the peroxo and bis(μ-oxo) forms of [Cu2O2]2+, comparable to other state-of-the-art quantum chemical methods.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/10.1063/1.4832476