Coupled cluster and perturbation theories based on a cluster mean-field reference applied to strongly correlated spin systems

Abstract

We introduce perturbation and coupled-cluster theories based on a cluster mean-field reference for describing the ground state of strongly-correlated spin systems. In cluster mean-field, the ground state wavefunction is written as a simple tensor product of optimized cluster states. The cluster language and the mean-field nature of the ansatz allows for a straightforward improvement which uses perturbation theory and coupled-cluster to account for inter-cluster correlations. We present benchmark calculations on the 1D chain and 2D square $J_1-J_2$ Heisenberg model, using cluster mean-field, perturbation theory and coupled-cluster. We also present an extrapolation scheme that allows us to compute thermodynamic limit energies accurately. Our results indicate that, with sufficiently large clusters, the correlated methods (cPT2, cPT4 and cCCSD) can provide a relatively accurate description of the Heisenberg model in the regimes considered, which suggests that the methods presented can be used for other strongly-correlated systems. Some ways to improve upon the methods presented in this work are discussed.

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Cited by in corpus (7)

• Symmetry-projected cluster mean-field theory applied to spin systems
• Linear combinations of cluster mean-field states applied to spin systems
• FragPT2: Multi-Fragment Wavefunction Embedding with Perturbative Interactions
• Efficient simulation of inhomogeneously correlated systems using block interaction product states
• Ground states of Heisenberg spin clusters from a cluster-based projected Hartree-Fock approach
• Coupled electron pair-type approximations for tensor product state wavefunctions
• Symmetry-Projected Spin-AGP Methods Applied to Spin Systems