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Title: Projected coupled cluster theory

Journal Article · · Journal of Chemical Physics
DOI:https://doi.org/10.1063/1.4991020· OSTI ID:1474042

Coupled cluster theory is the method of choice for weakly correlated systems. But in the strongly correlated regime, it faces a symmetry dilemma, where it either completely fails to describe the system or has to artificially break certain symmetries. On the other hand, projected Hartree-Fock theory captures the essential physics of many kinds of strong correlations via symmetry breaking and restoration. Here, we combine and try to retain the merits of these two methods by applying symmetry projection to broken symmetry coupled cluster wave functions. The non-orthogonal nature of states resulting from the application of symmetry projection operators furnishes particle-hole excitations to all orders, thus creating an obstacle for the exact evaluation of overlaps. Here we provide a solution via a disentanglement framework theory that can be approximated rigorously and systematically. Results of projected coupled cluster theory are presented for molecules and the Hubbard model, showing that spin projection significantly improves unrestricted coupled cluster theory while restoring good quantum numbers. The energy of projected coupled cluster theory reduces to the unprojected one in the thermodynamic limit, albeit at a much slower rate than projected Hartree-Fock.

Research Organization:
Temple Univ., Philadelphia, PA (United States). Center for the Computational Design of Functional Layered Materials (CCDM); Rice Univ., Houston, TX (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES); National Science Foundation (NSF); Welch Foundation
Grant/Contract Number:
SC0012575; CHE-1462434
OSTI ID:
1474042
Alternate ID(s):
OSTI ID: 1374781
Journal Information:
Journal of Chemical Physics, Vol. 147, Issue 6; ISSN 0021-9606
Publisher:
American Institute of Physics (AIP)Copyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 48 works
Citation information provided by
Web of Science

References (27)

On the use of general symmetry-projected Hartree–Fock–Bogoliubov configurations in variational approaches to the nuclear many-body problem journal April 2004
Bridging Single- and Multireference Domains for Electron Correlation: Spin-Extended Coupled Electron Pair Approximation journal March 2017
Merging symmetry projection methods with coupled cluster theory: Lessons from the Lipkin model Hamiltonian journal February 2017
Symmetry broken and restored coupled-cluster theory: I. Rotational symmetry and angular momentum journal December 2014
Combining symmetry collective states with coupled-cluster theory: Lessons from the Agassi model Hamiltonian journal June 2017
Bound states of a many-particle system journal June 1958
A Critical Assessment of Coupled Cluster Method in Quantum Chemistry book January 1999
Many – Body Methods in Chemistry and Physics book January 2009
Thermodynamic limit and size-consistent design journal June 2011
Benchmark variational coupled cluster doubles results journal November 2000
Absence of Mott Transition in an Exact Solution of the Short-Range, One-Band Model in One Dimension journal July 1968
Communication: Projected Hartree Fock theory as a polynomial similarity transformation theory of single excitations journal September 2016
Stability conditions and nuclear rotations in the Hartree-Fock theory journal November 1960
Projected Hartree–Fock theory journal April 2012
Attenuated coupled cluster: a heuristic polynomial similarity transformation incorporating spin symmetry projection into traditional coupled cluster theory journal January 2017
Electron correlations in narrow energy bands journal November 1963
On the Correlation Problem in Atomic and Molecular Systems. Calculation of Wavefunction Components in Ursell‐Type Expansion Using Quantum‐Field Theoretical Methods journal December 1966
Projected Hartree-Fock theory as a polynomial of particle-hole excitations and its combination with variational coupled cluster theory journal May 2017
Polynomial similarity transformation theory: A smooth interpolation between coupled cluster doubles and projected BCS applied to the reduced BCS Hamiltonian journal March 2016
Explicitly connected expansion for the average value of an observable in the coupled-cluster theory journal November 1993
Moeller-Plesset perturbation theory with spin projection journal June 1988
Spin-projected coupled-cluster theory with single and double excitations journal December 2000
Symmetry broken and restored coupled-cluster theory I. Rotational symmetry and angular momentum text January 2014
Bridging single- and multireference domains for electron correlation: spin-extended coupled electron pair approximation preprint January 2016
Projected Hartree-Fock as a Polynomial of Particle-Hole Excitations and Its Combination With Variational Coupled Cluster Theory text January 2017
Combining symmetry collective states with coupled cluster theory: Lessons from the Agassi model Hamiltonian text January 2017
Spin-Projected Generalized Hartree-Fock as a Polynomial of Particle-Hole Excitations text January 2017

Cited By (8)

Extending spin-symmetry projected coupled-cluster to large model spaces using an iterative null-space projection technique: Extending spin-symmetry projected coupled-cluster to large model spaces using an iterative null-space projection technique journal December 2018
Orbital-invariant spin-extended approximate coupled-cluster for multi-reference systems journal July 2018
Projected coupled cluster theory: Optimization of cluster amplitudes in the presence of symmetry projection journal October 2018
Efficient formulation of full configuration interaction quantum Monte Carlo in a spin eigenbasis via the graphical unitary group approach journal September 2019
Geminal-based configuration interaction journal August 2019
Energy of fermionic ground states with low-entanglement single-reference expansions, and tensor-based strong-coupling extensions of the coupled-cluster method journal January 2020
Pre-processing the nuclear many-body problem: Importance truncation versus tensor factorization techniques journal June 2019
Pre-processing the nuclear many-body problem: Importance truncation versus tensor factorization techniques text January 2019