Brueckner Orbitals in Local Pair Natural Orbital Coupled-Cluster Theory: DLPNO-BCCD(T) and DLPNO-BCCD(T)_Lambda2
Abstract
In this work, we implement closed-shell Brueckner orbitals for the efficient domain-based local pair natural orbital DLPNO-CCSD(T) and DLPNO-CCSD(T)Λ methods of the free and open-source \textsc{Psi4} package. We introduce a new algorithm that allows Brueckner orbitals to be computed within the DLPNO framework, resulting in the novel DLPNO-BCCD(T) and DLPNO-BCCD(T)Λ2 methods. We show that DLPNO-BCCD(T) approximates its canonical BCCD(T) counterpart with significantly lower errors relative to the errors incurred by DLPNO-CCSD(T) over CCSD(T). Through a test on the S22 set of noncovalent dimers, the peak error across the set is reduced from 0.36 kcal mol−1 to 0.25 kcal mol−1 using normal cutoffs, and 0.28 kcal mol−1 to 0.13 kcal mol−1 at tight cutoffs. In addition, we show that BCCD(T)Λ2, a Λ2-only implementation of Brueckner orbitals for the asymmetric triples method, generally produces the best agreement with CCSDT, compared to the (T), (T)Λ, and B(T) perturbative triples corrections. This is established through benchmarks on thermochemistry tests on the barrier heights of semibullvalene and bullvalene Cope rearrangement, while the robustness of DLPNO-BCCD(T)Λ2 is demonstrated along bond-breaking potential energy curves, where it matches the orbital-optimized quasi-variational asymmetric renormalized-triples OQVCCDAR(T) method closely for single-bond breaking, and approximates DLPNO-CCSDT respectably even when triple bonds are stretched, at a fraction of the computational cost.
Related
- Accelerating Periodic Coupled Cluster and Algebraic Diagrammatic Construction Theories With Frozen Natural Orbitals
- Shell-nested virtual spaces from atomic natural orbitals
- Low-Cost Third-order Algebraic Diagrammatic Construction Method for Excited States Using Tensor Hypercontraction and State-Specific Frozen Natural Orbitals
- A linear-scaling explicitly correlated local natural orbital CCSD(T) approach
- Bringing coupled‑cluster theory to the strong-correlation frontier
BibTeX
@misc{jiang2026brueckner,
title = {{Brueckner Orbitals in Local Pair Natural Orbital Coupled-Cluster Theory: DLPNO-BCCD(T) and DLPNO-BCCD(T)_Lambda2}},
author = {Andy Jiang and Tibor Gyori and Elizabeth C. Toth and Gabor Czako and Henry F. Schaefer III},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.06600},
eprint = {2611.06600},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.06600},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Brueckner Orbitals in Local Pair Natural Orbital Coupled-Cluster Theory: DLPNO-BCCD(T) and DLPNO-BCCD(T)_Lambda2
AU - Andy Jiang
AU - Tibor Gyori
AU - Elizabeth C. Toth
AU - Gabor Czako
AU - Henry F. Schaefer III
PY - 2026
DA - 2026/11/04
PB - arXiv
DO - 10.48550/arxiv.2611.06600
UR - https://arxiv.org/abs/2611.06600
AB - In this work, we implement closed-shell Brueckner orbitals for the efficient domain-based local pair natural orbital DLPNO-CCSD(T) and DLPNO-CCSD(T)_Λ methods of the free and open-source \textsc{Psi4} package. We introduce a new algorithm that allows Brueckner orbitals to be computed within the DLPNO framework, resulting in the novel DLPNO-BCCD(T) and DLPNO-BCCD(T)_Λ_2 methods. We show that DLPNO-BCCD(T) approximates its canonical BCCD(T) counterpart with significantly lower errors relative to the errors incurred by DLPNO-CCSD(T) over CCSD(T). Through a test on the S22 set of noncovalent dimers, the peak error across the set is reduced from 0.36 kcal mol^−1 to 0.25 kcal mol^−1 using normal cutoffs, and 0.28 kcal mol^−1 to 0.13 kcal mol^−1 at tight cutoffs. In addition, we show that BCCD(T)_Λ_2, a Λ_2-only implementation of Brueckner orbitals for the asymmetric triples method, generally produces the best agreement with CCSDT, compared to the (T), (T)_Λ, and B(T) perturbative triples corrections. This is established through benchmarks on thermochemistry tests on the barrier heights of semibullvalene and bullvalene Cope rearrangement, while the robustness of DLPNO-BCCD(T)_Λ_2 is demonstrated along bond-breaking potential energy curves, where it matches the orbital-optimized quasi-variational asymmetric renormalized-triples OQVCCDAR(T) method closely for single-bond breaking, and approximates DLPNO-CCSDT respectably even when triple bonds are stretched, at a fraction of the computational cost.
ER -